BACKGROUND: Cancer immunotherapy with transgenic T-cell receptor-engineered T cells (TCR-T) enables the targeting of intracellular tumor-specific antigens; in contrast, chimeric antigen receptor-modified T cells (CAR-T) mediate tumor cell killing via the recognition of surface antigens. In the case of acute myeloid leukemia, the lack of leukemia-specific surface antigens limits the efficacy of CAR-T cells; therefore, TCR-T cells may represent a more targeted immunotherapy approach. However, the tumor immunosuppressive environment eliminates the best-functioning, high-avidity TCR-T cells, thus creating a need for novel, enhanced TCR-T cells. METHODS: The piggyBac transposon vector used for gene modification of T cells expresses a T-cell receptor specific to the WT1 tumour antigen, an NFAT promoter-regulated CAR specific to GM-CSF receptor, a CD3xCD33 bispecific T-cell engager, and a truncated EGFR suicide gene system. The transgenic T cells were generated by electroporation using a single expression vector, and the efficiency of these engineered TCR-T cells was evaluated using models that utilized AML cell lines and primary AML cells. RESULTS: The NFAT-driven GM-CSF CAR significantly enhances the antileukemic activity of WT1-specific TCR-T cells, which importantly maintain specificity for their HLA/peptide antigenic complex. Next, by inserting the CD3xCD33 bispecific T-cell engager into the transposon vector, both TCR-T cells and recruited non-transfected bystander T cells can efficiently target the CD33 antigen, providing more robust antileukemic effects. CONCLUSION: The presented strategy, utilizing a single piggyBac transposon vector, enables the complex redirection of T-cell specificity against acute myeloid leukemia by inserting TCR, CAR, BiTE constructs, along with a tEGFR gene suicide system.

• Klíčová slova
• WT1, acute myeloid leukemia, chimeric antigen receptor, piggyBac transposon, transgenic T-cell receptor,
• Publikační typ
• časopisecké články MeSH

BACKGROUND: The non-viral production of CAR-T cells through electroporation of transposon DNA plasmids is an alternative approach to lentiviral/retroviral methods. This method is particularly suitable for early-phase clinical trials involving novel types of CAR-T cells. The primary disadvantage of non-viral methods is the lower production efficiency compared to viral-based methods, which becomes a limiting factor for CAR-T production, especially in chemotherapy-pretreated lymphopenic patients. METHODS: We describe a good manufacturing practice (GMP)-compliant protocol for producing CD19 and CD123-specific CAR-T cells based on the electroporation of transposon vectors. The lymphocytes were purified from the blood of patients undergoing chemotherapy for B-NHL or AML and were electroporated with piggyBac transposon encoding CAR19 or CAR123, respectively. Electroporated cells were then polyclonally activated by anti-CD3/CD28 antibodies and a combination of cytokines (IL-4, IL-7, IL-21). The expansion was carried out in the presence of irradiated allogeneic blood-derived mononuclear cells (i.e., the feeder) for up to 21 days. RESULTS: Expansion in the presence of the feeder enhanced CAR-T production yield (4.5-fold in CAR19 and 9.3-fold in CAR123). Detailed flow-cytometric analysis revealed the persistence of early-memory CAR-T cells and a low vector-copy number after production in the presence of the feeder, with no negative impact on the cytotoxicity of feeder-produced CAR19 and CAR123 T cells. Furthermore, large-scale manufacturing of CAR19 carried out under GMP conditions using PBMCs obtained from B-NHL patients (starting number=200x10e6 cells) enabled the production of >50x10e6 CAR19 in 7 out of 8 cases in the presence of the feeder while only in 2 out of 8 cases without the feeder. CONCLUSIONS: The described approach enables GMP-compatible production of sufficient numbers of CAR19 and CAR123 T cells for clinical application and provides the basis for non-viral manufacturing of novel experimental CAR-T cells that can be tested in early-phase clinical trials. This manufacturing approach can complement and advance novel experimental immunotherapeutic strategies against human hematologic malignancies.

• Klíčová slova
• CAR-T cells, PiggyBac PB transposon, electroporation, leukemia, lymphoma,
• MeSH
• akutní myeloidní leukemie * terapie   imunologie   genetika   MeSH
• allogeneické buňky imunologie   MeSH
• antigeny CD19 * imunologie   genetika   MeSH
• B-buněčný lymfom terapie   imunologie   genetika   MeSH
• chimerické antigenní receptory * genetika   imunologie   MeSH
• elektroporace MeSH
• imunoterapie adoptivní * metody   MeSH
• lidé MeSH
• podkladové buňky MeSH
• T-lymfocyty imunologie   metabolismus   MeSH
• transpozibilní elementy DNA * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antigeny CD19 * MeSH
• chimerické antigenní receptory * MeSH
• transpozibilní elementy DNA * MeSH

Tisagenlecleucel (tisa-cel) is a CD19-specific CAR-T cell product approved for the treatment of relapsed/refractory (r/r) DLBCL or B-ALL. We have followed a group of patients diagnosed with childhood B-ALL (n = 5), adult B-ALL (n = 2), and DLBCL (n = 25) who were treated with tisa-cel under non-clinical trial conditions. The goal was to determine how the intensive pretreatment of patients affects the produced CAR-T cells, their in vivo expansion, and the outcome of the therapy. Multiparametric flow cytometry was used to analyze the material used for manufacturing CAR-T cells (apheresis), the CAR-T cell product itself, and blood samples obtained at three timepoints after administration. We present the analysis of memory phenotype of CD4/CD8 CAR-T lymphocytes (CD45RA, CD62L, CD27, CD28) and the expression of inhibitory receptors (PD-1, TIGIT). In addition, we show its relation to the patients' clinical characteristics, such as tumor burden and sensitivity to prior therapies. Patients who responded to therapy had a higher percentage of CD8+CD45RA+CD27+ T cells in the apheresis, although not in the produced CAR-Ts. Patients with primary refractory aggressive B-cell lymphomas had the poorest outcomes which was characterized by undetectable CAR-T cell expansion in vivo. No clear correlation of the outcome with the immunophenotypes of CAR-Ts was observed. Our results suggest that an important parameter predicting therapy efficacy is CAR-Ts' level of expansion in vivo but not the immunophenotype. After CAR-T cells' administration, measurements at several timepoints accurately detect their proliferation intensity in vivo. The outcome of CAR-T cell therapy largely depends on biological characteristics of the tumors rather than on the immunophenotype of produced CAR-Ts.

• Klíčová slova
• B-cell lymphoma and leukemia, CAR-T cells, Kymriah, immunotherapy, tisagenlecleucel,
• MeSH
• B-buněčný lymfom * MeSH
• CD8-pozitivní T-lymfocyty metabolismus   MeSH
• difúzní velkobuněčný B-lymfom * patologie   MeSH
• imunoterapie adoptivní metody   MeSH
• lidé MeSH
• průtoková cytometrie MeSH
• receptory antigenů T-buněk metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• receptory antigenů T-buněk MeSH
• tisagenlecleucel MeSH Prohlížeč

The piggyBac transposon system provides a non-viral alternative for cost-efficient and simple chimeric antigen receptor (CAR) T cell production. The generation of clinical-grade CAR T cells requires strict adherence to current good manufacturing practice (cGMP) standards. Unfortunately, the high costs of commonly used lentiviral or retroviral vectors limit the manufacturing of clinical-grade CAR T cells in many non-commercial academic institutions. Here, we present a manufacturing platform for highly efficient generation of CD19-specific CAR T cells (CAR19 T cells) based on co-electroporation of linear DNA transposon and mRNA encoding the piggyBac transposase. The transposon is prepared enzymatically in vitro by PCR and contains the CAR transgene flanked by piggyBac 3' and 5' arms. The mRNA is similarly prepared via in vitro transcription. CAR19 T cells are expanded in the combination of cytokines interleukin (IL)-4, IL-7, and IL-21 to prevent terminal differentiation of CAR T cells. The accurate control of vector copy number (VCN) is achieved by decreasing the concentration of the transposon DNA, and the procedure yields up to 1 × 108 CAR19 T cells per one electroporation of 1 × 107 peripheral blood mononuclear cells (PBMCs) after 21 days of in vitro culture. Produced cells contain >60% CAR+ cells with VCN < 3. In summary, the described manufacturing platform enables a straightforward cGMP certification, since the transposon and transposase are produced abiotically in vitro via enzymatic synthesis. It is suitable for the cost-effective production of highly experimental, early-phase CAR T cell products.

• Klíčová slova
• CD19, T cells, chimeric antigenic receptor, electroporation, piggyBac transposon,
• Publikační typ
• časopisecké články MeSH