Optimized conditions for gene transduction into primary immune cells using viral vectors.

Chimeric antigen receptor (CAR) T cell therapy has emerged as a promising modality for anti-cancer treatment. Its efficacy is quite remarkable in hematological tumors. Owing to their excellent clinical results, gene- modified cell therapies, including T cells, natural killer (NK) cells, and macrophages, are being actively studied in both academia and industry. However, the protocol to make CAR immune cells is too complicated, so it is still unclear how to efficiently produce the potent CAR immune cells. To manufacture effective CAR immune cells, we need to be aware of not only how to obtain highly infective viral particles, but also how to transduce CAR genes into immune cells. In this paper, we provide detailed information on spinoculation, which is one of the best known protocols to transduce genes into immune cells, in a methodological view. Our data indicate that gene transduction is significantly dependent on speed and duration of centrifugation, concentration and number of viral particles, the concentration of polybrene, and number of infected immune cells. In addition, we investigated on the optimal polyethylene glycol (PEG) solution to concentrate the viral supernatant and the optimized DNA ratios transfected into 293T cells to produce high titer of viral particles. This study provides useful information for practical production of the gene-modified immune cells using viral vectors.

Structure-activity relationship analysis of novel GSPT1 degraders based on benzotriazinone scaffold and its antitumor effect on xenograft mouse model.

Molecular glue degraders, such as lenalidomide and pomalidomide, bind to cereblon (CRBN) E3 ligase and subsequently recruit neosubstrate proteins, Ikaros (IKZF1) and Aiolos (IKZF3), for the ubiquitination-proteasomal degradation process. In this study, we explored structure-activity relationship analysis for novel GSPT1 degraders utilizing a benzotriazinone scaffold previously discovered as a novel CRBN binder. In particular, we focused on the position of the ureido group on the benzotriazinone scaffold, substituent effect on the phenylureido group, and methyl substitution on the benzylic position of benzotriazinone. As a result, we identified 34f (TD-522), which exhibits strong anti-proliferative effects in both KG-1 (EC50 = 0.5 nM) and TMD-8 (EC50 = 5.2 nM) cell lines. Compound 34f effectively induced GSPT1 degradation with a DC50 of 0.269 nM and Dmax of >95 % at 10 nM concentration in KG-1 cells. An in vivo xenograft study showed that compound 34f effectively suppressed TMD8-driven tumor growth, suggesting a potential role in the development of novel GSPT1 degraders.

Development of Antigen-specific Chimeric Antigen Receptor KHYG-1 Cells for Glioblastoma.

BACKGROUND/AIM: Glioblastoma is the most common cancer among primary brain tumors, however, its prognosis and treatment advances are very poor. Here, we investigated whether c-Met, FOLR1, and AXL proteins are promising targets for chimeric antigen receptor (CAR) T-cell therapy, for they are known to be over-expressed in a variety of solid tumors. MATERIALS AND METHODS: CAR constructs were prepared and CAR KHYG-1 cells targeting c-Met, FOLR1, or AXL were made by lentiviral transduction. The activity of CAR KHYG-1 cells against cancer cells was measured by cytokine secretion and cell lysis assays. RESULTS: c-Met and AXL were over-expressed in most glioblastoma cell lines (11/13), but not in neuroblastoma cell lines (0/8). FOLR1 was over-expressed only in one among 16 glioblastoma cell lines. Our antigen-specific CAR KHYG-1 cells eradicated target positive glioblastoma cells selectively. CONCLUSION: Anti-c-Met and anti-AXL CAR NK or T cells could be effective in glioblastoma cells.

Identification of Potent CD19 scFv for CAR T Cells through scFv Screening with NK/T-Cell Line.

CD19 is the most promising target for developing chimeric-antigen receptor (CAR) T cells against B-cell leukemic cancer. Currently, two CAR-T-cell products, Kymriah and Yescarta, are approved for leukemia patients, and various anti-CD19 CAR T cells are undergoing clinical trial. Most of these anti-CD19 CAR T cells use FMC63 single-chain variable fragments (scFvs) for binding CD19 expressed on the cancer cell surface. In this study, we screened several known CD19 scFvs for developing anti-CD19 CAR T cells. We used the KHYG-1 NK/T-cell line for screening of CD19 scFvs because it has advantages in terms of cell culture and gene transduction compared to primary T cells. Using our CAR construct backbone, we made anti-CD19 CAR constructs which each had CD19 scFvs including FMC63, B43, 25C1, BLY3, 4G7, HD37, HB12a, and HB12b, then made each anti-CD19 CAR KHYG-1 cells. Interestingly, only FMC63 CAR KHYG-1 and 4G7 CAR KHYG-1 efficiently lysed CD19-positive cell lines. In addition, in Jurkat cell line, only these two CAR Jurkat cell lines secreted IL-2 when co-cultured with CD19-positive cell line, NALM-6. Based on these results, we made FMC63 CAR T cells and 4G7 CAR T cells from PBMC. In in vitro lysis assay, 4G7 CAR T cells lysed CD19-positive cell line as well as FMC63 CAR T cells. In in vivo assay with NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) mice, 4G7 CAR T cells eradicated NALM-6 as potently as FMC63 CAR T cells. Therefore, we anticipate that 4G7 CAR T cells will show as good a result as FMC63 CAR T cells for B-cell leukemia patients.

A Chemical Switch System to Modulate Chimeric Antigen Receptor T Cell Activity through Proteolysis-Targeting Chimaera Technology.

Despite the excellent efficacy of chimeric antigen receptor (CAR T) cell therapy, concerns about its safety have been constantly raised. The side effects of CAR T cells result from an aberrantly upregulation of CAR T cell activity. Therefore, it is crucial to control the CAR T cell activity whenever the patient is at risk. For this purpose, the iCas9 system, which induces apoptosis in CAR T cell through caspase-9 dimerization by compound, has been invented and is currently going under clinical trial. However, the iCas9 system is irreversible, as the entire CAR T cell population is removed from the patient. Thus, CAR T cells, which are very expensive, should be reinfused to the patients after they recovered from the side-effect. Here, we propose a new CAR T cell safety strategy, which targets CAR "protein", not CAR "T cell". In this system, the CAR construct is modified to bear a bromodomain (BD). The addition of a BD in the CAR protein did not interfere with the original CAR functions, such as cytokine secretion and target cell lysis. Our data showed that the use of a proteolysis-targeting chimaera (PROTAC) compound against BD successfully degraded the BD-containing CAR protein. Moreover, the CAR expression is recovered when the PROTAC compound is removed from the cell, demonstrating that our system is reversible. In a target cell lysis assay, the PROTAC compound successfully suppressed the lytic activity of CAR T cells by degrading the CAR protein. In conclusion, we developed a new safety system in which CAR T cells can be "reversibly" controlled by a compound.