Universal chimeric Fcγ receptor T cells with appropriate affinity for IgG1 antibody exhibit optimal antitumor efficacy

Developing universal CARs with improved flexible targeting and controllable activities is urgently needed. While several studies have suggested the potential of CD16a in tandem with monoclonal antibodies to construct universal CAR-T cells, the weak affinity between them is one of the limiting factors for efficacy. Herein, we systematically investigated the impact of Fcγ receptor (FcγR) affinity on CAR-T cells properties by constructing universal CARs using Fcγ receptors with different affinities for IgG1 antibodies, namely CD16a, CD32a, and CD64. We demonstrated that the activities of these universal CAR-T cells on tumor cells could be redirected and regulated by IgG1 antibodies. In xenografted mice, 64CAR chimeric Jurkat cells with the highest affinity showed significant antitumor effects in combination with herceptin in the HER2 low expression U251 MG model. However, in the CD20 high expression Raji model, 64CAR caused excessive activation of CAR-T cells, which resulted in cytokine release syndrome (CRS) and the decline of antitumor activity, and 32CAR with a moderate affinity brought the best efficacy. Our work extended the knowledge about FcγR-based universal CAR-T cells and suggested that only the FcγRCAR with an appropriate affinity can offer the optimal antitumor advantages of CAR-T cells.

Imunoterapia com células CAR-T como nova perspectiva de tratamento da leucemia linfoblástica aguda recidivada/refratária / Immunotherapy with CAR-T cells as a new treatment perspective for relapsed/refractory acute lymphoblastic leukemia

Introdução: O tratamento da leucemia linfoblástica aguda (LLA) atualmente baseia-se em quimioterapia e/ou transplante de células tronco hematopoiéticas; entretanto, uma nova terapia vem se tornando promissora: a imunoterapia com células T modificadas geneticamente que expressam um receptor de antígeno quimérico (CAR-T) visando antígenos específicos presente em blastos de LLA, gerando resultados promissores em crianças e adultos com doença recidivada e refratária (r/r). Objetivo: Discorrer sobre a LLA e descrever a imunoterapia com CAR-T, como inovação terapêutica no tratamento da LLA de linhagem B. Método: Foi realizada uma revisão bibliográfica por meio de publicações indexadas nas bases de dados Scielo e Pubmed, utilizando os descritores: leucemia linfoblástica aguda de células B; células CAR-T; receptores de antígeno quimérico, recidivados/refratários; imunoterapia. Resultados: As altas taxas de remissão completa (42% até 100%) e parcial (28,5%) da LLA (r/r) tratadas com CAR-T, possibilitam um aumento considerável da sobrevida geral comparado a outros tratamentos convencionais. Efeitos desfavoráveis, tais como síndrome da liberação de citocinas (CRS) (0 até 90%) e neurotoxicidade (NT) (0 até 29%) podem ser vistos, sendo manejáveis, não prejudicando o desfecho do tratamento. Conclusão: A LLA é uma doença grave, de difícil tratamento e prognóstico reservado. A imunoterapia vêm se mostrando promissora à essa enfermidade, principalmente em casos de doença r/r se mostrado uma ferramenta poderosa que permite o foco específico de células malignas por meio de engenharia de células T

Introduction: The treatment of acute lymphoblastic leukemia (ALL) is currently based on chemotherapy and/or hematopoietic stem cell transplantation; however, a new therapy is becoming promising: immunotherapy with genetically modified T cells that express a chimeric antigen receptor (CAR-T) targeting specific antigens present on ALL blasts, reaching promising results in children and adults with relapsed and refractory disease (r/r). Objective: To discuss ALL and describe immunotherapy with CAR-T as a therapeutic innovation in the treatment of B-lineage ALL. Method: A literature review was carried out through publications indexed in the Scielo and Pubmed databases, using the following descriptors: B-cell acute lymphoblastic leukemia; CAR-T cells; chimeric antigen receptors, relapsed/refractory; immunotherapy. Results: The high rates of complete (42% to 100%) and partial remission (28.5%) of ALL (r/r) treated with CAR-T allows a considerable increase in overall survival compared to other conventional treatments. Unfavorable effects such as cytokine release syndrome (CRS) (0 to 90%) and neurotoxicity (NT) (0 to 29%) can be seen, being manageable, not impairing the treatment outcome. Conclusion: ALL is a serious disease, with a difficult treatment and poor prognosis. Immunotherapy has shown benefits for this disease, especially in cases of r/r ALL, showing itself to be a powerful tool that allows the specific focus of malignant cells through T cell engineering.

CAR T-cell immunotherapy: a powerful weapon for fighting hematological B-cell malignancies / 医学前沿

The current standard of care in hematological malignancies has brought considerable clinical benefits to patients. However, important bottlenecks still limit optimal achievements following a current medical practice. The genetic complexity of the diseases and the heterogeneity of tumor clones cause difficulty in ensuring long-term efficacy of conventional treatments for most hematological disorders. Consequently, new treatment strategies are necessary to improve clinical outcomes. Chimeric antigen receptor T-cell (CAR T) immunotherapy opens a new path for targeted therapy of hematological malignancies. In this review, through a representative case study, we summarize the current experience of CAR T-cell therapy, the management of common side effects, the causative mechanisms of therapy resistance, and new strategies to improve the efficacy of CAR T-cell therapy.

Establishment of a simple and efficient platform for car-t cell generation and expansion: from lentiviral production to in vivo studies

ABSTRACT Introduction: Adoptive transfer of T cells expressing a CD19-specific chimeric antigen receptor (CAR) has shown impressive response rates for the treatment of CD19 + B-cell malignancies in numerous clinical trials. The CAR molecule, which recognizes cell-surface tumor-associated antigen independently of human leukocyte antigen (HLA), is composed by one or more signaling molecules to activate genetically modified T cells for killing, proliferation, and cytokine production. Objectives: In order to make this treatment available for a larger number of patients, we developed a simple and efficient platform to generate and expand CAR-T cells. Methods: Our approach is based on a lentiviral vector composed by a second-generation CAR that signals through a 41BB and CD3-ζ endodomain. Conclusions: In this work, we show a high-level production of the lentiviral vector, which was successfully used to generate CAR-T cells. The CAR-T cells produced were highly cytotoxic and specific against CD19+ cells in vitro and in vivo, being able to fully control disease progression in a xenograft B-cell lymphoma mouse model. Our work demonstrates the feasibility of producing CAR-T cells in an academic context and can serve as a paradigm for similar institutions. Nevertheless, the results presented may contribute favoring the translation of the research to the clinical practice.

Programming CAR T cells to enhance anti-tumor efficacy through remodeling of the immune system / 医学前沿

Chimeric antigen receptor (CAR) T cells have been indicated effective in treating B cell acute lymphoblastic leukemia and non-Hodgkin lymphoma and have shown encouraging results in preclinical and clinical studies. However, CAR T cells have achieved minimal success against solid malignancies because of the additional obstacles of their insufficient migration into tumors and poor amplification and persistence, in addition to antigen-negative relapse and an immunosuppressive microenvironment. Various preclinical studies are exploring strategies to overcome the above challenges. Mobilization of endogenous immune cells is also necessary for CAR T cells to obtain their optimal therapeutic effect given the importance of the innate immune responses in the elimination of malignant tumors. In this review, we focus on the recent advances in the engineering of CAR T cell therapies to restore the immune response in solid malignancies, especially with CAR T cells acting as cellular carriers to deliver immunomodulators to tumors to mobilize the endogenous immune response. We also explored the sensitizing effects of conventional treatment approaches, such as chemotherapy and radiotherapy, on CAR T cell therapy. Finally, we discuss the combination of CAR T cells with biomaterials or oncolytic viruses to enhance the anti-tumor outcomes of CAR T cell therapies in solid tumors.

Current advances in chimeric antigen receptor T-cell therapy for refractory/relapsed multiple myeloma / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

multiple myeloma (MM), considered an incurable hematological malignancy, is characterized by its clonal evolution of malignant plasma cells. Although the application of autologous stem cell transplantation (ASCT) and the introduction of novel agents such as immunomodulatory drugs (IMiDs) and proteasome inhibitors (PIs) have doubled the median overall survival to eight years, relapsed and refractory diseases are still frequent events in the course of MM. To achieve a durable and deep remission, immunotherapy modalities have been developed for relapsed/refractory multiple myeloma (RRMM). Among these approaches, chimeric antigen receptor (CAR) T-cell therapy is the most promising star, based on the results of previous success in B-cell neoplasms. In this immunotherapy, autologous T cells are engineered to express an artificial receptor which targets a tumor-associated antigen and initiates the T-cell killing procedure. Tisagenlecleucel and Axicabtagene, targeting the CD19 antigen, are the two pacesetters of CAR T-cell products. They were approved by the US Food and Drug Administration (FDA) in 2017 for the treatment of acute lymphocytic leukemia (ALL) and diffuse large B-cell lymphoma (DLBCL). Their development enabled unparalleled efficacy in combating hematopoietic neoplasms. In this review article, we summarize six promising candidate antigens in MM that can be targeted by CARs and discuss some noteworthy studies of the safety profile of current CAR T-cell therapy.

Construction of a novel lentiviral vector knocking down PD-1 via microRNA and its application in CAR-T cells / 生物工程学报

By inserting microRNAs into the intron of EF1α promoter, we constructed a novel lentiviral vector knocking down PD-1 gene via microRNA and applied it to CAR-T cells. Lentiviral transduction efficiency and PD-1-silencing efficiency were detected by flow cytometry. PD-1 expression was detected by Western blotting. Relative expression of microRNA was measured by Q-PCR. Cytotoxicity of CAR-T cells based on this vector was tested by luciferase bioluminescence and flow cytometry. Compared with lentiviral vector with microRNA transcribed by U6 promotor, the transduction efficiency of lentiviral vector with microRNA which was inserted into the intron of EF1α promoter was more significant, and the knockdown rate of PD-1 was more than 90%, which was validated by flow cytometry and Western blotting. And the relative expression level of microRNA in Jurkat cells transduced with this novel lentiviral vector was shown by Q-PCR. Compared with normal CAR-T cells, CAR-T cells based on this vector showed stronger cytotoxicity against PD-L1 positive Raji cells. We successfully constructed a novel lentiviral vector that knocked down PD-1 via microRNA and verified the superiority of its transduction efficiency and knockdown efficiency of PD-1. CAR-T cells based on this vector can exert a more powerful cytotoxicity, thus providing theoretical support for the subsequent treatment of PD-L1 positive tumors.

Linfocitos T modificados por ingeniería genética: ¿Una nueva esperanza para el tratamiento del glioblastoma? / Genetically modified T lymphocytes: A new hope for glioblastoma treatment?

Resumen El glioblastoma es uno de los tumores primarios del sistema nervioso central más agresivos, debido a su alta capacidad de generar resistencia a la mayoría de los tratamientos oncológicos disponibles actualmente. Asimismo, este tumor tiene un elevado potencial de recidiva y genera una mortalidad alta entre los individuos afectados. Por lo tanto, existe una urgente necesidad por contar con nuevas estrategias terapéuticas que permitan lograr una mayor tasa de remisión y una mejor sobrevida en los pacientes con glioblastoma. Novedosos avances en inmunoterapia, como la generación de linfocitos T autólogos modificados por ingeniería genética, prometen ser agentes terapéuticos capaces de proveer un grado considerable de control sobre diferentes tipos de cánceres. En el presente artículo, se comentan los resultados de algunas investigaciones recientes sobre el uso específico de esta estrategia para el manejo de individuos con glioblastoma.

Abstract Glioblastoma is among the most aggressive primary tumors of the central nervous system due to its high capacity to acquire resistance to many of the currently available oncologic treatments. Likewise, this tumor possesses an elevated potential for recurrence generating a high mortality among affected individuals. Therefore, there is an urgent necessity for new therapeutic strategies to achieve a higher remission rate and a better survival rate in patients with glioblastoma. New advances in immunotherapy, such as the production of autologous T lymphocytes modified by genetic engineering, are promissory therapeutic agents capable of providing a considerable degree of control over different types of cancers. In this article, we discuss the results of some recent studies

PD-1 expression, mRNA level and cytotoxicity changes in CD19CAR-T cells / 中华血液学杂志

Objective@#To observe the changes of PD-1 expression, mRNA level and cytotoxic activity of CD19 CAR-T cells during the culture process of CAR-T cells.@*Methods@#The peripheral blood T cells of 6 lymphoma patients with high expression of PD-1 and 6 healthy volunteers were the source of CAR-T cells. The expression of PD-1 was analyzed by flow cytometry. The mRNA level of PD-1 was analyzed by PCR. The cell proliferation was analyzed by CCK-8 assay. The cytotoxicity was analyzed by LDH assay.@*Results@#①The transfection efficiency of high PD-1 expression T cells and healthy volunteer T cells were as the same (P>0.05) . ②The cell proliferation capacity of CD19 CAR-T cells from high PD-1 expression T cells or healthy volunteer T cells, with or without PD-1 inhibitor were as the same (P>0.05) . ③The cytotoxicity to lymphoma cells of high PD-1 expression T cells and CAR-T cells were lower than that of these two T cells combined with PD-1 inhibitor and the CAR-T cells from healthy volunteer T cells (P<0.001) . There was no difference of the cytotoxicity between the CAR-T cells from high PD-1 expression T cells combined with PD-1 inhibitor and the CAR-T cells from healthy volunteer (P>0.05) . ④There was no difference of the expression of PD-1 in all CAR-T cell groups during the culture process (P>0.05) . There was no difference of mRNA level of PD-1 in all groups during the culture process (P>0.05) . ⑤The PD-1 expression of CAR-T cells increased by the time of culture after contacting with lymphoma cells (P<0.001) . The PD-1 inhibitors could antagonize this effect. There was no difference of mRNA level of PD-1 in all groups after contacting with lymphoma cells (P>0.05) .@*Conclusion@#The PD-1 expression of CAR-T cells from high PD-1 expression T cells increased by the time of culture after contacting with lymphoma cells. However, the mRNA level of PD-1 of all groups did not change, even if PD-1 inhibitor was applied.

Ibrutinib combined with CAR-T cells in the treatment of del (17p) chronic lymphocytic leukemia with BCL-2 inhibitor resistance: a case report and literature review / 中华血液学杂志

Objective@#To improve the knowledge and experience of ibrutinib combined with CAR-T cells in the treatment of high-risk chronic lymphoblastic leukemia (CLL) patients or small lymphocytic lymphoma (SLL) with TP53 gene aberration.@*Methods@#One case of del (17p) CLL patients with BCL-2 inhibitor resistance was treated with ibrutinib combined with CAR-T cells, successfully bridged to allogeneic hematopoietic stem cell transplantation (allo-HSCT) , and the relative literatures were reviewed.@*Results@#The patient was a young female with superficial lymph node enlarging at the beginning of the onset. Lymph node biopsy was confirmed as small lymphocytic lymphoma (SLL) without del (17p) . The disease progressed rapidly to CLL/SLL with del (17p) and bone marrow hematopoietic failure 2 years later. Firstly, the patient was treated with BCL-2 inhibitor (Venetoclax) , and the enlarged lymph nodes shrank significantly 2 months later. After 3 months, the disease progressed rapidly. The spleen was enlarged to 16 cm below the ribs, the neck lymph nodes was rapidly enlarged, and the superior vena cava syndrome appeared, which were mainly attributed to venetoclax resistance; so BTK inhibitor (ibrutinib) was used continuously after venetoclax discontinuation. Partial remission (PR) was achieved without lymphocytosis after 2 months, then ibrutinib was combined with CAR-T cells targeting CD19 antigen. Grade 1 of cytokine release syndrome (CRS) appeared after CAR-T cells infusion, and the complete remission (CR) was achieved after 1 month both in bone marrow and peripheral blood, with minimal residual disease (MRD) negative, then bridging allo-HSCT after 2 months of combined therapy.@*Conclusion@#CLL/SLL patients with TP53 aberration have poor prognosis because of rapid progression, drug resistance, etc. Ibrutinib combined with CAR-T cell therapy can quickly achieved complete remission.

In vitro and in vivo cytotoxic activity of humanized CD19 CAR-T cells against Raji cell line / 中华微生物学和免疫学杂志

Objective@#To investigate the different functions of humanized and murinized CD19 chimeric antigen receptor (CAR)-T cells against Raji cell line in vitro and in vivo.@*Methods@#Peripheral blood samples were collected from eight patients with lymphoma who were going to receive CD19 CAR-T cell therapy and used for the preparation of peripheral blood mononuclear cells (PBMC) as well as humanized and murinized CAR-T cells. Cell proliferation and cytotoxicity were detected with CCK-8 and LDH assays, respectively. A tumor-bearing mouse model was established by injecting BALB/c female nude mice with fluorescent Raji cells. Changes in tumor volume in these mice were observed by in vivo imaging technology. The transfection efficiency and amount of CAR-T cells in the mice were detected with flow cytometry.@*Results@#No statistical difference in transfection efficiency was found between humanized and murinized CAR-T cells, nor in cell proliferation at 24 h of culture in vitro(P=0.104). The proliferation of humanized CAR-T cells showed a significant increase compared with that of murinized CAR-T cells at 48 h of culture (P=0.009). Similarly, the cytotoxicity of the two types of CAR-T cells against Raji cells showed no significant difference at 24 h at any effector/target (E/T) ratio (1∶1 or 4∶1), and that of humanized CAR-T cells was higher than that of murinized CAR-T cells at both E/T ratios at 48 h (E/T ratio=1∶1, P=0.005; E/T ratio=4∶1, P=0.008). Moreover, the cytotoxicity of CAR-T cells was higher than that of PBMC in any case. Tumor volumes in mice were reduced 14 d after humanized or murinized CAR-T cell therapy, while the mice in the PBMC control group suffered tumor progression. Tumor volume began to increase in mice 21 d after murinized CAR-T cell therapy, while no significant change was observed in the mice treated with humanized CAR-T cells. All of the mice died 25 d after murinized CAR-T cell therapy, while the deaths among those under humanized CAR-T cell therapy occurred on 31 d. The proportion of CAR-T cells in mice reached the peak 7 d after receiving humanized or murinized CAR-T cell therapy, while that in the humanized group was significantly higher than that in the murinized group at any time point (P4 d=0.001, P7 d=0.000, P14 d=0.003). Murinized CAR-T cells became undetectable on 21 d, while humanized CAR-T cells on 35 d. The maximum survival time for mice in the PBMC and murinized and humanized CAR-T cell groups was 20 d, 25 d and 53 d, respectively.@*Conclusions@#Compared with murinized CD19 CAR-T cells, humanized CD19 CAR-T cells showed stronger proliferation potential and cytotoxicity and remained in vivo detectable for a longer period of time. This study indicated that humanized CD19 CAR-T cells were superior to murinized CD19 CAR-T cells for the treatment of B cell lymphoma.

In vitro and in vivo cytotoxic activity of humanized CD19 CAR-T cells against Raji cell line / 中华微生物学和免疫学杂志

Objective To investigate the different functions of humanized and murinized CD19 chimeric antigen receptor ( CAR)-T cells against Raji cell line in vitro and in vivo. Methods Peripheral blood samples were collected from eight patients with lymphoma who were going to receive CD19 CAR-T cell therapy and used for the preparation of peripheral blood mononuclear cells ( PBMC) as well as humanized and murinized CAR-T cells. Cell proliferation and cytotoxicity were detected with CCK-8 and LDH assays, respectively. A tumor-bearing mouse model was established by injecting BALB/c female nude mice with flu-orescent Raji cells. Changes in tumor volume in these mice were observed by in vivo imaging technology. The transfection efficiency and amount of CAR-T cells in the mice were detected with flow cytometry. Re-sults No statistical difference in transfection efficiency was found between humanized and murinized CAR-T cells, nor in cell proliferation at 24 h of culture in vitro(P=0. 104). The proliferation of humanized CAR-T cells showed a significant increase compared with that of murinized CAR-T cells at 48 h of culture ( P=0. 009). Similarly, the cytotoxicity of the two types of CAR-T cells against Raji cells showed no significant difference at 24 h at any effector/target (E/T) ratio (1 : 1 or 4 : 1), and that of humanized CAR-T cells was higher than that of murinized CAR-T cells at both E/T ratios at 48 h (E/T ratio=1 : 1, P=0. 005;E/T ratio=4 : 1, P=0. 008). Moreover, the cytotoxicity of CAR-T cells was higher than that of PBMC in any case. Tumor volumes in mice were reduced 14 d after humanized or murinized CAR-T cell therapy, while the mice in the PBMC control group suffered tumor progression. Tumor volume began to increase in mice 21 d after murinized CAR-T cell therapy, while no significant change was observed in the mice treated with hu-manized CAR-T cells. All of the mice died 25 d after murinized CAR-T cell therapy, while the deaths among those under humanized CAR-T cell therapy occurred on 31 d. The proportion of CAR-T cells in mice reached the peak 7 d after receiving humanized or murinized CAR-T cell therapy, while that in the humanized group was significantly higher than that in the murinized group at any time point (P4 d=0. 001, P7 d=0. 000, P14 d=0. 003). Murinized CAR-T cells became undetectable on 21 d, while humanized CAR-T cells on 35 d. The maximum survival time for mice in the PBMC and murinized and humanized CAR-T cell groups was 20 d, 25 d and 53 d, respectively. Conclusions Compared with murinized CD19 CAR-T cells, humanized CD19 CAR-T cells showed stronger proliferation potential and cytotoxicity and remained in vivo detectable for a longer period of time. This study indicated that humanized CD19 CAR-T cells were superior to murinized CD19 CAR-T cells for the treatment of B cell lymphoma.

Construction of HER2-specific CAR-T cells and in vitro analysis of their activity to suppress tumor cell growth / 生物工程学报

CAR-T cell therapy that targets surface antigens to kill tumor cells specifically has recently become another cornerstone in tumor immunotherapy. In this study, a lentiviral expression plasmid of CAR targeting human epidermal growth factor receptor 2 (HER2) was constructed by genetic engineering. The recombinant plasmid was co-transfected with other packaging plasmids into HEK293T cells by calcium phosphate precipitation to generate lenti-car, which are CAR lentiviral particles. HER2-specific CAR-T cells were obtained by transducing human peripheral blood mononuclear cells with lenti-car. Their specific inhibitory effects on HER2-positive and HER2-negative tumor cells were analyzed in vitro. The constructed CAR-T cells were specifically activated by HER2-expressing tumor cells as indicated by secretion of IFN-γ and IL-2. The inhibitory rate on HER2-positive SK-OV-3 cell line was (58.47±1.72)%, significantly higher than that on the mock-treated control group (P<0.05). The inhibitory rate on HER2-negative K562 cell lines was (11.74±2.37)%, which was not significantly different from that on the control group (P>0.05). Furthermore, when we transfected a HER2-expressing vector into K562, the inhibitory rate increased to (30.41±7.59)%, which was higher than that on HER2-negative K562 (P<0.05). Thus, the constructed second-generation HER2-specific CAR-T cells specifically suppressed growth of tumor cells overexpressing HER2 protein, suggesting that HER2-specific CAR-T cells might prove useful for immunotherapy of HER2-positive cancer.