Woodchuck Hepatitis Virus Post-Transcriptional Regulation Element (WPRE) Promotes Anti-CD19 BiTE Expression in Expi293 Cells.

Background: Bispecific antibodies represent an important class of monoclonal antibodies (mAbs), with great therapeutic potentials due to their ability to target simultaneously two distinct epitopes. The generation of functional bispecific antibodies with the highest possible yields is particularly critical for the production of these compounds on industrial scales. Anti-CD3 × CD19 bispecific antibody (bsAb) is a bispecific T-cell engager currently used for treating ALL. Herein, we have tried to optimize the expression level of this antibody in mammalian hosts. Methods: Woodchuck hepatitis virus post-transcriptional regulation (WPRE) sequence was incorporated at the 3' end of the expression cassette. This modification resulted in a notable about two-fold increase in the expression of the bsAb in the Expi293 cell line. Results & Conclusion: Follow-up flow cytometry analysis demonstrated the binding properties of the produced antibody at acceptable levels, and in vitro bioactivity assays showed that this product is potent enough for targeting and destroying CD19-positive cells. Our findings show that WPRE enhances the expression of this type of bispecific mAbs in human embryonic kidney-293 family cell lines. This approach can be used in biopharma industry for the mass production of anti-CD3 × CD19 bispecific antibody.

Bi/tri-specific antibodies (HN-Fc-CD16 and HN-Fc-IL-15-CD16) cross-linking natural killer (NK)-CD16 and Newcastle Disease Virus (NDV)-HN, enhanced NK activation for cancer immunotherapy.

Cancer/tumor cells infected with the "avian paramyxovirus Newcastle Disease Virus (TC-NDV)" express the viral hemagglutinin-neuraminidase (HN) on the cell surface that is used as both the danger signal and anchor for bi/tri-specific antibodies (bs/tsAbs).We constructed a bs-Ab (HN-Fc-CD16) that bindsto HN and natural killer (NK)-CD16 receptor (FcgRIII)and a ts-Ab (HN-Fc-IL15-CD16) harbouring NK-activating cytokine "IL-15" within the bs-Ab.In silicoand computational predictions indicated proper exposure of both Abs in bs/tsAbs.Properbinding of thebi/tsAbstoHN on surface of TC-NDVandCD16+-cells was demonstrated by flow cytometry.The bi/tsAbstriggeredspecificcytotoxicity of NK cells againstTC-NDVand elicited substantial IFN-γproduction by activated NK cells(higher for ts-Ab) that sound promising for cancer immunotherapy purposes.

Engineered Jurkat Cells for Targeting Prostate-Specific Membrane Antigen on Prostate Cancer Cells by Nanobody-Based Chimeric Antigen Receptor

Background: Recently, modification of T cells with chimeric antigen receptor (CAR) has been an attractive approach for adoptive immunotherapy of cancers. Typically, CARs contain a single-chain variable domain fragment (scFv). Most often, scfvs are derived from a monoclonal antibody of murine origin and may be a trigger for host immune system that leads to the T-cell clearance. Nanobody is a specific antigen-binding fragment derived from camelid that has great homology to human VH and low immunogenic potential. Therefore, in this study, nanobody was employed instead of scFv in CAR construct. Methods: In this study, a CAR was constructed based on a nanobody against PSMA (NBPII-CAR). At first, Jurkat cells were electroporated with NBPII-CAR, and then flow cytometry was performed for NBPII-CAR expression. For functional analysis, CAR T cells were co-cultured with prostate cancer cells and analyzed for IL-2 secretion, CD25 expression, and cell proliferation. Results: Flow cytometry results confirmed the expression of NBPII-CAR on the transfected Jurkat cells. Our data showed the specificity of engineered Jurkat cells against prostate cancer cells by not only increasing the IL-2 cytokine (about 370 pg/ml) but also expressing the T-cell activation marker CD25 (about 30%). In addition, proliferation of engineered Jurkat cells increased nearly 60% when co-cultured with LNCaP (PSMA+), as compared with DU145 (PSMA-). Conclusion: Here, we describe the ability of nanobody-based CAR to recognize PSMA that leads to the activation of Jurkat cells. This construct might be used as a promising candidate for clinical applications in prostate cancer therapy.

T cell engineered with a novel nanobody-based chimeric antigen receptor against VEGFR2 as a candidate for tumor immunotherapy.

Solid tumors that are responsible for more than 85% of cancer death cases need angiogenesis for their growth and metastasis. Among antiangiogenic therapies, targeting the vascular endothelial growth factor receptor 2 (VEGFR2) that is over-expressed on tumor vasculatures has been a promising strategy. In this study, we developed a second generation nanobody (VHH)-based CAR T cell targeting VEGFR2-expressing tumor cells. The CAR T cell was developed by linking the anti-VEGFR2 VHH to a spacer, and signaling domains of CD28 and CD3 ζ. The T cells were activated with anti-CD3 plus rIL-2 and electroporated with a plasmid encoding the CAR construct. The expression of activation markers, CD69 and CD25, on CAR T cells upon coculturing with VEGFR2-expressing cells were 41% and 48%, and the IL-2 and IFN-γ production were 470 pg/mL and 360 pg/mL, respectively. The expression of degranulation marker, CD107a, was 30% and the cytotoxic activity of the CAR T cells reached to more than 30% with E:T ratio of 9:1. The anti-VEGFR2 CAR but not mock T cells mediated specific lysis of 293-KDR cells expressing human VEGFR2 and might be considered as a candidate for adoptive T-cell immunotherapy of solid tumors. © 2019 IUBMB Life, 71(9):1259-1267, 2019.

Construction of a chimeric antigen receptor bearing a nanobody against prostate a specific membrane antigen in prostate cancer.

Adoptive transfer of T cells expressing chimeric antigen receptors (CARs) is considered to be a novel anticancer therapy. To date, in most cases, single-chain variable fragments (scFvs) of murine origin have been used in CARs. However, this structure has limitations relating to the potential immunogenicity of mouse antigens in humans and the relatively large size of scFvs. For the first time, we used camelid nanobody (VHH) to construct CAR T cells against prostate specific membrane antigen (PSMA). The nanobody against PSMA (NBP) was used to show the feasibility of CAR T cells against prostate cancer cells. T cells were transfected, and then the surface expression of the CAR T cells was confirmed. Then, the functions of VHH-CAR T cell were evaluated upon coculture with prostate cancer cells. At the end, the cytotoxicity potential of NBPII-CAR in T cells was approximated by determining the cell surface expression of CD107a after encountering PSMA. Our data show the specificity of VHH-CAR T cells against PSMA+ cells (LNCaP), not only by increasing the interleukin 2 (IL-2) cytokine (about 400 pg/mL), but also the expression of CD69 by almost 38%. In addition, VHH-CAR T cells were proliferated by nearly 60% when cocultured with LNCaP, as compared with PSMA negative prostate cancer cell (DU-145), which led to the upregulation of CD107a in T cells upto 31%. These results clearly show the possibility of using VHH-based CAR T cells for targeted immunotherapy, which may be developed to target virtually any tumor-associated antigen for adoptive T-cell immunotherapy of solid tumors.

The effect of Candida albicans systemic infection on matrix metalloproteinases in breast cancer bearing BALB/c mice.

Breast cancer patients are susceptible to infections such as candidiasis. Due to the importance and the role of matrix metalloproteinases (MMP) in breast cancer progression and its correlation with tumor metastasis, we analyzed the serum level of MMPs -2, -3, -9 and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) in breast cancer bearing mice in the presence of systemic Candida albicans infection. Female BALB/c mice were divided into 4 groups: group I had tumor + candidiasis; group II, tumor only; group III, candidiasis only and group IV as negative control. Tumor tissue was separated from stock breast cancer bearing mice and transplanted subcutaneously into the groups I and II mice. Two weeks after tumor transplantation, groups I and III were infected with Candida albicans by intravenous injection. One week after systemic infection, the sera of the experimental groups were prepared and analyzed with ELISA for MMP-2, -3, -9 and TIMP-1 levels. The results showed that the levels of MMP-3, MMP-9 and TIMP-1 were increased in groups I, II and III, as compared to the control group. However, the level of MMP-2 was decreased in mice infected with Candida albicans and in infected mice bearing tumor. These data suggest that candidiasis may have a positive effect on tumor progression and metastasis.