Adoptive Chimeric Antigen Receptor Research Articles

Scalable intracellular delivery via microfluidic vortex shedding enhances the function of chimeric antigen receptor T-cells.

Adoptive chimeric antigen receptor T-cell (CAR-T) therapy is transformative and approved for hematologic malignancies. It is also being developed for the treatment of solid tumors, autoimmune disorders, heart disease, and aging. Despite unprecedented clinical outcomes, CAR-T and other engineered cell therapies face a variety of manufacturing and safety challenges. Traditional methods, such as lentivirus transduction and electroporation, result in random integration or cause significant cellular damage, which can limit the safety and efficacy of engineered cell therapies. We present hydroporation as a gentle and effective alternative for intracellular delivery. Hydroporation resulted in 1.7- to 2-fold higher CAR-T yields compared to electroporation with superior cell viability and recovery. Hydroporated cells exhibited rapid proliferation, robust target cell lysis, and increased pro-inflammatory and regulatory cytokine secretion in addition to improved CAR-T yield by day 5 post-transfection. We demonstrate that scaled-up hydroporation can process 5 × 108 cells in less than 10 s, showcasing the platform as a viable solution for high-yield CAR-T manufacturing with the potential for improved therapeutic outcomes.

Scalable intracellular delivery via microfluidic vortex shedding enhances the function of chimeric antigen receptor T-cells.

Adoptive chimeric antigen receptor T-cell (CAR-T) therapy is transformative and approved for hematologic malignancies. It is also being developed for the treatment of solid tumors, autoimmune disorders, heart disease, and aging. Despite unprecedented clinical outcomes, CAR-T and other engineered cell therapies face a variety of manufacturing and safety challenges. Traditional methods, such as lentivirus transduction and electroporation, result in random integration or cause significant cellular damage, which can limit the safety and efficacy of engineered cell therapies. We present hydroporation as a gentle and effective alternative for intracellular delivery. Hydroporation resulted in 1.7- to 2-fold higher CAR-T yields compared to electroporation with superior cell viability and recovery. Hydroporated cells exhibited rapid proliferation, robust target cell lysis, and increased pro-inflammatory and regulatory cytokine secretion in addition to improved CAR-T yield by day 5 post-transfection. We demonstrate that scaled-up hydroporation can process 5 x 108 cells in less than 10 s, showcasing the platform as a viable solution for high-yield CAR-T manufacturing with the potential for improved therapeutic outcomes.

Risk of Second Tumors and T-Cell Lymphoma after CAR T-Cell Therapy

BackgroundThe risk of second tumors after chimeric antigen receptor (CAR) T-cell therapy, especially the risk of T-cell neoplasms related to viral vector integration, is an emerging concern.MethodsWe reviewed our clinical experience with adoptive cellular CAR T-cell therapy at our institution since 2016 and ascertained the occurrence of second tumors. In one case of secondary T-cell lymphoma, a broad array of molecular, genetic, and cellular techniques were used to interrogate the tumor, the CAR T cells, and the normal hematopoietic cells in the patient.ResultsA total of 724 patients who had received T-cell therapies at our center were included in the study. A lethal T-cell lymphoma was identified in a patient who had received axicabtagene ciloleucel therapy for diffuse large B-cell lymphoma, and both lymphomas were deeply profiled. Each lymphoma had molecularly distinct immunophenotypes and genomic profiles, but both were positive for Epstein–Barr virus and were associated with DNMT3A and TET2 mutant clonal hematopoiesis. No evidence of oncogenic retroviral integration was found with the use of multiple techniques.ConclusionsOur results highlight the rarity of second tumors and provide a framework for defining clonal relationships and viral vector monitoring. (Funded by the National Cancer Institute and others.)

Immunometabolic Maladaptations to the Tumor Microenvironment.

Tumors consist of cancer cells and a wide range of tissue resident and infiltrating cell types. Tumor metabolism, however, has largely been studied on whole tumors or cancer cells and the metabolism of infiltrating immune cells remains poorly understood. It is now clear from a range of analyses and metabolite rescue studies that metabolic adaptations to the tumor microenvironment (TME) directly impede T-cell and macrophage effector functions. The drivers of metabolic adaptation to the TME and metabolic immune suppression include depletion of essential nutrients, accumulation of waste products or immune suppression metabolites, and metabolic signaling through altered posttranslational modifications. Each infiltrating immune cell subset differs, however, with specific metabolic requirements and adaptations that can be maladaptive for antitumor immunity. Here, we review T-cell and macrophage adaptation and metabolic immune suppression in solid tumors. Ultimately, understanding and addressing these challenges will improve cancer immunotherapy and adoptive chimeric antigen receptor T-cell therapies.

Present Status and Advances in Chimeric Antigen Receptor T Cell Therapy for Glioblastoma.

Adoptive chimeric antigen receptor (CAR) T cells designed to recognize specific tumor antigens have shown promising results in cancer therapy. While CAR T cell therapy has demonstrated notable clinical effectiveness for hematologic disease, efforts to develop therapies for solid tumors, including glioblastoma (GBM), have been hampered by heterogeneity, an immunosuppressive tumor microenvironment, and difficulty in trafficking. Several specific tumor antigens, such as IL13Rα2, EGFRvIII, and HER2, have been attempted in clinical trials; however, limited efficacy has been observed. In this review, we discuss the current status of CAR T therapy for GBM in clinical trials and highlight the potential target antigens for CAR T cells. Additionally, we summarize the mechanisms used to enhance their efficacy and explore the challenges and future prospects of CAR T cell therapy for GBM.

Engineered human pluripotent stem cell-derived natural killer cells with PD-L1 responsive immunological memory for enhanced immunotherapeutic efficacy

Adoptive chimeric antigen receptor (CAR)-engineered natural killer (NK) cells have shown promise in treating various cancers. However, limited immunological memory and access to sufficient numbers of allogenic donor cells have hindered their broader preclinical and clinical applications. Here, we first assess eight different CAR constructs that use an anti-PD-L1 nanobody and/or universal anti-fluorescein (FITC) single-chain variable fragment (scFv) to enhance antigen-specific proliferation and anti-tumor cytotoxicity of NK-92cells against heterogenous solid tumors. We next genetically engineer human pluripotent stem cells (hPSCs) with optimized CARs and differentiate them into functional dual CAR-NK cells. The tumor microenvironment responsive anti-PD-L1 CAR effectively promoted hPSC-NK cell proliferation and cytotoxicity through antigen-dependent activation of phosphorylated STAT3 (pSTAT3) and pSTAT5 signaling pathways via an intracellular truncated IL-2 receptor β-chain (ΔIL-2Rβ) and STAT3-binding tyrosine-X-X-glutamine (YXXQ) motif. Anti-tumor activities of PD-L1-induced memory-like hPSC-NK cells were further boosted by administering a FITC-folate bi-specific adapter that bridges between a programmable anti-FITC CAR and folate receptor alpha-expressing breast tumor cells. Collectively, our hPSC CAR-NK engineering platform is modular and could constitute a realistic strategy to manufacture off-the-shelf CAR-NK cells with immunological memory-like phenotype for targeted immunotherapy.

Engagement of an optimized lentiviral vector enhances the expression and cytotoxicity of CAR in human NK cells.

Adoptive chimeric antigen receptor (CAR)-modified T or NK cells (CAR-T/NK) have emerged as a novel form of disease treatment. Lentiviral vectors (LVs) are commonly employed to engineer NK cells for the efficient expression of CARs. This study reported the influence of single-promoter and dual-promoter LVs on the CAR expression and cytotoxicity of engineered NK cells. We constructed a third-generation NKG2D-based CAR that kills cancer cells by targeting up to eight stress-induced ligands (NKG2DLs). Our results demonstrated that the CAR exhibits both a higher expression level and a higher coexpression concordance with the GFP reporter in HEK-293T or NK92 cells by utilizing the optimized single-promoter pCDHsp rather than the original dual-promoter pCDHdp. After puromycin selection, the pCDHsp produces robust CAR expression and enhanced in vitro cytotoxicity of engineered NK cells. Therefore, infection with a single-promoter pCDHsp lentivector is recommended to prepare CAR-engineered NK cells. This research helps to optimize the production of CAR-NK cells and enhance their functional activity, to provide CAR-NK cell products with better and more uniform quality.

CD318 is a target of chimeric antigen receptor T cells for the treatment of colorectal cancer.

Colorectal cancer (CRC) currently has a poor prognosis with a 6.9-year median survival time; to relieve this malignant cancer, we proposed to establish CRC xenografts that can be used to evaluate the cytotoxicity of adoptive chimeric antigen receptor (CAR)-T cells and accelerate the clinical translation of CAR-T cells for use against CRC. We first verified that CD318 had a higher expression level in primary human CRC tissues than in normal tissues based on hundreds of clinical samples. Then, we redirected CAR-T cells containing anti-CD318 single-chain variable fragment (anti-CD318 scFv), CD3ζ, CD28, and Toll-like receptor 2 (TLR2) domains. Next, we evaluated the function of these CAR-T cells in vitro in terms of surface phenotype changes, cytotoxicity and cytokine secretion when they encountered CD318+ CRC cells. Finally, we established two different xenograft mouse models to assess in vivo antitumor activity. The results showed that CAR318 T cells were significantly activated and exhibited strong cytotoxicity and cytokine-secreting abilities against CRC cells in vitro. Furthermore, CAR318 T cells induced CRC regression in different xenograft mouse models and suppressed tumors compared with CAR19 T cells. In summary, our work demonstrates that CAR318 T cells possess strong antitumor capabilities and represent a promising therapeutic approach for CRC.

Recent advances in CAR-T cells therapy for colorectal cancer.

Colorectal cancer (CRC) is the third most common cancer, with a high mortality rate and a serious impact on people’s life and health. In recent years, adoptive chimeric antigen receptor T (CAR-T) cells therapy has shown well efficacy in the treatment of hematological malignancies, but there are still many problems and challenges in solid tumors such as CRC. For example, the tumor immunosuppressive microenvironment, the low targeting of CAR-T cells, the short time of CAR-T cells in vivo, and the limited proliferation capacity of CAR-T cells, CAR-T cells can not effectively infiltrate into the tumor and so on. New approaches have been proposed to address these challenges in CRC, and this review provides a comprehensive overview of the current state of CAR-T cells therapy in CRC.

EXTH-37. PAK4 INHIBITION REPROGRAMS VASCULAR MICROENVIRONMENT AND IMPROVES CAR T IMMUNOTHERAPY IN GLIOBLASTOMA

Abstract Malignant solid tumors are characterized by aberrant vascularity that inhibits T cell adhesion to vasculature and impedes T cell delivery into the tumors, contributing to glioblastoma (GBM) resistance to T cell-based immunotherapy such as adoptive chimeric antigen receptor (CAR)–T transfer. Vascular abnormality is driven by pro-angiogenic pathway activation and genetic reprogramming in tumor endothelial cells (ECs). Here, our kinome-wide functional screening of mesenchymal-like transcriptional activation in human GBM-derived ECs identifies p21-activated kinase 4 (PAK4) as a selective regulator of genetic programming and aberrant vascularization in tumor. Genetic ablation of PAK4 reprograms EC transcriptome and inhibits mesenchymal-like transformation. Interestingly, deficiency of PAK4 induces adhesion protein re-expression in tumor ECs, reduces vascular abnormalities in tumors, improves T cell infiltration into the tumors, and inhibits GBM growth in mice. Moreover, pharmacological PAK4 inhibition normalizes the tumor vascular microenvironment and sensitizes GBM to Egfrviii CAR–T cell immunotherapy. Finally, we reveal a MEF2D/ZEB1- and SLUG-mediated mechanism by which PAK4 reprograms the EC transcriptome and downregulates claudin-14 and VCAM-1 expression, enhancing vessel permeability and reducing T cell adhesion to the endothelium. Thus, targeting PAK4-mediated EC plasticity may offer exciting opportunities to recondition the vascular microenvironment and strengthen cancer immunotherapy.

Hematopoietic versus Solid Cancers and T Cell Dysfunction: Looking for Similarities and Distinctions.

Simple SummaryDysfunction of the immune T cell compartment occurs in many hematopoietic as well as solid cancers and hampers successful application of new immunotherapeutic approaches. A complete understanding of T cell dysfunction might improve the outcome of such therapies, but an overview in the various cancers is still lacking. We aim to map areas of similarities and differences in solid versus hematopoietic malignancies, providing a high-level rather than a detailed perspective on T cell dysfunction in those tumors.Cancer cells escape, suppress and exploit the host immune system to sustain themselves, and the tumor microenvironment (TME) actively dampens T cell function by various mechanisms. Over the last years, new immunotherapeutic approaches, such as adoptive chimeric antigen receptor (CAR) T cell therapy and immune checkpoint inhibitors, have been successfully applied for refractory malignancies that could only be treated in a palliative manner previously. Engaging the anti-tumor activity of the immune system, including CAR T cell therapy to target the CD19 B cell antigen, proved to be effective in acute lymphocytic leukemia. In low-grade hematopoietic B cell malignancies, such as chronic lymphocytic leukemia, clinical outcomes have been tempered by cancer-induced T cell dysfunction characterized in part by a state of metabolic lethargy. In multiple myeloma, novel antigens such as BCMA and CD38 are being explored for CAR T cells. In solid cancers, T cell-based immunotherapies have been applied successfully to melanoma and lung cancers, whereas application in e.g., breast cancer lags behind and is modestly effective as yet. The main hurdles for CAR T cell immunotherapy in solid tumors are the lack of suitable antigens, anatomical inaccessibility, and T cell anergy due to immunosuppressive TME. Given the wide range of success and failure of immunotherapies in various cancer types, it is crucial to comprehend the underlying similarities and distinctions in T cell dysfunction. Hence, this review aims at comparing selected, distinct B cell-derived versus solid cancer types and at describing means by which malignant cells and TME might dampen T cell anti-tumor activity, with special focus on immunometabolism. Drawing a meaningful parallel between the efficacy of immunotherapy and the extent of T cell dysfunction will shed light on areas where we can improve immune function to battle cancer.

A metabolic switch to memory CAR T cells: Implications for cancer treatment.

Therapeutic efficacy of chimeric antigen receptor (CAR) T cells is associated with their expansion, persistence and effector function. Although CAR T cell therapy has shown remarkable therapeutic effects in hematological malignancies, its therapeutic efficacy has been limited in some types of cancers - in particular, solid tumors - partially due to the cells' inability to persist and the acquisition of T cell dysfunction within a harsh immunosuppressive tumor microenvironment. Therefore, it would be expected that generation of CAR T cells with intrinsic properties for functional longevity, such as the cells with early-memory phenotypes, could beneficially enhance antitumor immunity. Furthermore, because the metabolic pathways of CAR T cells help determine cellular differentiation and lifespan, therapies targeting such pathways like glycolysis and oxidative phosphorylation, can alter CAR T cell fate and durability within tumors. Here we discuss how reprogramming of CAR T cell metabolism and metabolic switch to memory CAR T cells influences their antitumor activity. We also offer potential strategies for targeting these metabolic circuits in the setting of adoptive CAR T cell therapy, aiming to better unleash the potential of adoptive CAR T cell therapy in the clinic.

CD103+ cDC1 and endogenous CD8+ T cells are necessary for improved CD40L-overexpressing CAR T cell antitumor function

While effective in specific settings, adoptive chimeric antigen receptor (CAR) T cell therapy for cancer requires further improvement and optimization. Our previous results show that CD40L-overexpressing CAR T cells mobilize endogenous immune effectors, resulting in improved antitumor immunity. However, the cell populations required for this protective effect remain to be identified. Here we show, by analyzing Batf3−/− mice lacking the CD103+ conventional dendritic cell type 1 (cDC1) subpopulation important for antigen cross-presentation, that CD40L-overexpressing CAR T cells elicit an impaired antitumor response in the absence of cDC1s. We further find that CD40L-overexpressing CAR T cells stimulate tumor-resident CD11b−CD103− double-negative (DN) cDCs to proliferate and differentiate into cDC1s in wild-type mice. Finally, re-challenge experiments show that endogenous CD8+ T cells are required for protective antitumor memory in this setting. Our findings thus demonstrate the stimulatory effect of CD40L-overexpressing CAR T cells on innate and adaptive immune cells, and provide a rationale for using CD40L-overexpressing CAR T cells to improve immunotherapy responses.

Monitoring CAR T-cells using flow cytometry.

Chimeric antigen receptor (CAR) T-cell therapy is considered as a major scientific breakthrough in cancer immunotherapy. The success of adoptive CAR T-cell therapy for cancer has inspired researchers to expand indications into the area of solid tumors, autoimmune and infectious diseases. The most important factors influencing outcome and durability of the response after infusion of CAR T-cell are proliferation and persistence of this cell subset. It becomes therefore important to detect easily and monitor circulating CAR T-cells into blood samples. Approaches such as quantitative PCR (qPCR) or flow cytometry have been developed. The aim of this study was to set up and optimize a reachable flow cytometry technique using labeled CD19 protein for the measurement of CAR T-cells in infusion bag and patient's blood. Patients receiving Yescarta in Cell Therapy Unit (Department of hematology, Lille university hospital, France) between April and October 2019 and healthy volunteers were included to set up the flow cytometry technique. We assessed feasibility in clinic and suitability to routine workload of a flow cytometry technique to follow CAR T-cells in infusion bag and patient's blood. With only a few manual steps, the present protocol allows the technician to perform this technique among other routine tasks, meaning a time to results of <2 hr after sample reception. We were also able to assess CAR T-cell heterogenity in terms of CD4+ and CD8+ T lymphocytes within the subset. Moreover, this technique allows monitoring of both authority approved CD19 CAR T-cell.

CAR T Cells Beyond Cancer: Hope for Immunomodulatory Therapy of Infectious Diseases.

Infectious diseases are still a significant cause of morbidity and mortality worldwide. Despite the progress in drug development, the occurrence of microbial resistance is still a significant concern. Alternative therapeutic strategies are required for non-responding or relapsing patients. Chimeric antigen receptor (CAR) T cells has revolutionized cancer immunotherapy, providing a potential therapeutic option for patients who are unresponsive to standard treatments. Recently two CAR T cell therapies, Yescarta® (Kite Pharma/Gilead) and Kymriah® (Novartis) were approved by the FDA for the treatments of certain types of non-Hodgkin lymphoma and B-cell precursor acute lymphoblastic leukemia, respectively. The success of adoptive CAR T cell therapy for cancer has inspired researchers to develop CARs for the treatment of infectious diseases. Here, we review the main achievements in CAR T cell therapy targeting viral infections, including Human Immunodeficiency Virus, Hepatitis C Virus, Hepatitis B Virus, Human Cytomegalovirus, and opportunistic fungal infections such as invasive aspergillosis.

Constitutively active MyD88/CD40 costimulation enhances expansion and efficacy of chimeric antigen receptor T cells targeting hematological malignancies

Successful adoptive chimeric antigen receptor (CAR) T-cell therapies against hematological malignancies require CAR-T expansion and durable persistence following infusion. Balancing increased CAR-T potency with safety, including severe cytokine-release syndrome (sCRS) and neurotoxicity, warrants inclusion of safety mechanisms to control in vivo CAR-T activity. Here, we describe a novel CAR-T cell platform that utilizes expression of the toll-like receptor (TLR) adaptor molecule, MyD88, and tumor-necrosis factor family member, CD40 (MC), tethered to the CAR molecule through an intentionally inefficient 2A linker system, providing a constitutive signal that drives CAR-T survival, proliferation, and antitumor activity against CD19+ and CD123+ hematological cancers. Robust activity of MC-enhanced CAR-T cells was associated with cachexia in animal models that corresponded with high levels of human cytokine production. However, toxicity could be successfully resolved by using the inducible caspase-9 (iC9) safety switch to reduce serum cytokines, by administration of a neutralizing antibody against TNF-α, or by selecting “low” cytokine-producing CD8+ T cells, without loss of antitumor activity. Interestingly, high basal activity was essential for in vivo CAR-T expansion. This study shows that co-opting novel signaling elements (i.e., MyD88 and CD40) and development of a unique CAR-T architecture can drive T-cell proliferation in vivo to enhance CAR-T therapies.

Marrow-Infiltrating Lymphocytes (MILs) Provide a Robust Platform for CAR-T Cell Therapy

▪Adoptive cellular immunotherapy (ACT) using chimeric-antigen receptor (CAR)-modified T cells has shown unprecedented initial response rates in patients with advanced B cell malignancies and is emerging as a powerful tool for cancer treatment. However, there remains room for improvement in initial response rates, and relapse occurs in a significant fraction of those patients that do respond. Reasons for failure to respond are being elucidated. At least two mechanism of relapse - lack of persistence of infused CAR-T cells and the loss of antigen-expression by tumor cells - are well documented.We have developed a novel platform for ACT called Marrow-infiltrating Lymphocytes (MILs). MILs are a population of polyclonal T cells expanded from the bone marrow (BM) with distinct properties that set them apart from T cells expanded from peripheral blood lymphocytes (PBLs). MILs are enriched with memory T cells and contain tumor antigen-specific T cells that are typically not detected in PBLs. MILs are being developed for several tumor types, including both hematological and solid tumors.Distinguishing features of MILs compared to PBLs include their memory phenotype, inherent tumor antigen-specificity, and ability to persist long-term. As such, we hypothesized that MILs would provide a robust platform for CAR-T cell therapy with the potential to boost initial response rates and reduce the risk of relapse. Herein, data is presented demonstrating superior anti-tumor activity of CAR-modified MILs (CAR-MILs) compared to CAR-T cells generated from patient-matched PBLs (CAR-PBLs).We designed a 2nd generation 4-1BB-CD3z CD38 CAR using an scFv derived from Daratumumab. The CD38 CAR was linked to GFP by a T2a cleavage peptide so that GFP could be used as a marker of CAR expression. The CD38 CAR was expressed in a lentiviral construct and demonstrated equal transduction efficiencies and CAR expression levels in MILs and PBLs. The CAR modified MILs demonstrated superior antigen specific killing compared to PBLs against the 8226 myeloma (MM) cell line but not its isogenic CD38 knocked out line. More importantly, CAR-MILs retained their inherent tumor antigen-specificity and capacity to respond through their endogenous tumor antigen-specific T cell receptors - a property that PBL-CARs did not appear to possess. Tumor antigen-specific T cells were quantified by co-culturing MILs with autologous antigen-presenting cells pulsed with allogeneic multiple myeloma cell line lysates as a source of antigen and measuring IFNγ-production as a read-out. An equal or greater number of tumor antigen-specific IFNγ-producing T cells were measured in CD38 CAR-MILs compared to matched unmodified MILs.Finally, we compared the in vitro cytolytic potential of CD38 CAR-MILs to matched CD38 CAR-PBLs. Co-culture killing assays were performed at decreasing CAR-T effector: target (E:T) ratios. At high E:T ratios, CAR-MILs and CAR-PBLs lysed comparable percentages of CD38+ targets with similar kinetics. However, at lower E:T ratios, CAR-MILs killed a greater percentage of CD38+ targets with faster kinetics compared to CAR-PBLs.In conclusion, we have demonstrated 1) the feasibility of producing CAR-modified MILs, 2) that CAR-MILs retain their inherent tumor antigen-specificity and functional capacity - something that was lacking with CAR-PBLs, and 3) that CAR-MILs kill more efficiently in vitro than matched CAR-PBLs. These data suggest that CAR-MILs may provide both better antigen specific killing but more importantly by targeting the endogenous antigenic repertoire, they could also prevent or minimize the risk of relapse via antigen escape variants and thus increase the overall efficacy of adoptive CAR T cell therapy. DisclosuresLutz:WIndMIL Therapeutics: Employment, Patents & Royalties. Rudraraju:WIndMIL Therapeutics: Employment. DeOliveira:WIndMIL Therapeutics: Employment. Jana:WIndMIL Therapeutics: Employment. Weiss:WIndMIL Therapeutics: Employment. Borrello:WIndMIL Therapeutics: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. Noonan:WIndMIL Therapeutics: Employment, Equity Ownership, Patents & Royalties.

Bortezomib improves adoptive carbonic anhydraseIX‑specific chimeric antigen receptor‑modified NK92 cell therapy in mouse models of human renal cell carcinoma.

Adoptive chimeric antigen receptor (CAR) T or NK cells offer new options for cancer treatment. Clinical results indicate that CAR‑modified Tcell (CAR‑T) therapy has curative therapeutic efficacy for hematological malignancies. However, the efficacy of the therapy in most solid tumors, including advanced renal cell carcinoma (RCC), remains highly limited. New regimens, including combination of CAR‑T cells with chemical drugs, must be studied to enhance the therapeutic efficacy of CAR‑T or NK cells for solid tumors. In the present study, a carbonic anhydraseIX (CAIX)‑specific third‑generation CAR was transduced into NK92 cells by lentiviral vectors. The immune effects, including cytokine release and cytotoxicity, of the CAR‑NK92 cells against CAIX‑positive RCC cells were evaluated invitro. Combination therapeutic effects of bortezomib and CAR‑NK92 cells were analyzed in a mouse model with human RCC xenografts. The results revealed that CAIX‑specific CAR‑NK92 cells specifically recognized invitro cultured CAIX‑positive RCC cells and released cytokines, including IFN‑γ, perforin and granzymeB, and exhibited specific cytotoxicity. The cytotoxicity of the CAR‑NK92 cells was enhanced after treating RCC cells with bortezomib invitro. The suppressive efficacy of bortezomib combined with CAR‑NK92 cells against established CAIX‑positive tumor xenografts was more significant than that of the monotherapy with either CAR‑NK92 cells or bortezomib. Therefore, bortezomib can enhance the effects of the CAR‑NK92 cells against RCC invitro and invivo. This study provided an experimental basis for the novel clinical regimen of CAIX‑specific CAR‑modified NK or T cells for the treatment of RCC.

Nanobody Based Dual Specific CARs.

Recent clinical trials have shown that adoptive chimeric antigen receptor (CAR) T cell therapy is a very potent and possibly curative option in the treatment of B cell leukemias and lymphomas. However, targeting a single antigen may not be sufficient, and relapse due to the emergence of antigen negative leukemic cells may occur. A potential strategy to counter the outgrowth of antigen escape variants is to broaden the specificity of the CAR by incorporation of multiple antigen recognition domains in tandem. As a proof of concept, we here describe a bispecific CAR in which the single chain variable fragment (scFv) is replaced by a tandem of two single-antibody domains or nanobodies (nanoCAR). High membrane nanoCAR expression levels are observed in retrovirally transduced T cells. NanoCARs specific for CD20 and HER2 induce T cell activation, cytokine production and tumor lysis upon incubation with transgenic Jurkat cells expressing either antigen or both antigens simultaneously. The use of nanobody technology allows for the production of compact CARs with dual specificity and predefined affinity.

Anti-GPC3-CAR T Cells Suppress the Growth of Tumor Cells in Patient-Derived Xenografts of Hepatocellular Carcinoma

The lack of a general clinic-relevant model for human cancer is a major impediment to the acceleration of novel therapeutic approaches for clinical use. We propose to establish and characterize primary human hepatocellular carcinoma (HCC) xenografts that can be used to evaluate the cytotoxicity of adoptive chimeric antigen receptor (CAR) T cells and accelerate the clinical translation of CAR T cells used in HCC. Primary HCCs were used to establish the xenografts. The morphology, immunological markers, and gene expression characteristics of xenografts were detected and compared to those of the corresponding primary tumors. CAR T cells were adoptively transplanted into patient-derived xenograft (PDX) models of HCC. The cytotoxicity of CAR T cells in vivo was evaluated. PDX1, PDX2, and PDX3 were established using primary tumors from three individual HCC patients. All three PDXs maintained original tumor characteristics in their morphology, immunological markers, and gene expression. Tumors in PDX1 grew relatively slower than that in PDX2 and PDX3. Glypican 3 (GPC3)-CAR T cells efficiently suppressed tumor growth in PDX3 and impressively eradicated tumor cells from PDX1 and PDX2, in which GPC3 proteins were highly expressed. GPC3-CAR T cells were capable of effectively eliminating tumors in PDX model of HCC. Therefore, GPC3-CAR T cell therapy is a promising candidate for HCC treatment.