CAR T cells equipped with a fully human scFv targeting Trop2 can be used to treat pancreatic cancer.

PURPOSE: Chimeric antigen receptor (CAR) T cell therapy has demonstrated clinical success in treating haematologic malignancies but has not been effective against solid tumours thus far. Trop2 is a tumour-related antigen broadly overexpressed on a variety of tumours and has been reported as a promising target for pancreatic cancers. Our study aimed to determine whether CAR T cells designed with a fully human Trop2-specific single-chain fragment variable (scFv) can be used in the treatment of Trop2-positive pancreatic tumours. METHODS: We designed Trop2-targeted chimeric antigen receptor engineered T cells with a novel human anti-Trop2 scFv (2F11) and then investigated the cytotoxicity, degranulation, and cytokine secretion profiles of the anti-Trop2 CAR T cells when they were exposed to Trop2 + cancer cells in vitro. We also studied the antitumour efficacy and toxicity of Trop2-specific CAR T cells in vivo using a BxPC-3 pancreatic xenograft model. RESULTS: Trop2-targeted CAR T cells designed with 2F11 effectively killed Trop2-positive pancreatic cancer cells and produced high levels of cytotoxic cytokines in vitro. In addition, Trop2-targeted CAR T cells, which persistently circulate in vivo and efficiently infiltrate into tumour tissues, significantly blocked and even eliminated BxPC-3 pancreatic xenograft tumour growth without obvious deleterious effects observed after intravenous injection into NSG mice. Moreover, disease-free survival was efficiently prolonged. CONCLUSION: These results show that Trop2-targeted CAR T cells equipped with a fully human anti-Trop2 scFv could be a potential treatment strategy for pancreatic cancer and could be useful for clinical evaluation.

Feasibility study of a novel preparation strategy for anti-CD7 CAR-T cells with a recombinant anti-CD7 blocking antibody.

Although chimeric antigen receptor (CAR) T cell immunotherapy has shown promising significance in B cell malignancies, success against T cell malignancies remains unsatisfactory because of shared antigenicity between normal and malignant T cells, resulting in fratricide and hindering CAR production for clinical treatment. Here, we report a new strategy of blocking the CD7 antigen on the T cell surface with a recombinant anti-CD7 antibody to obtain a sufficient amount of CD7-targeting CAR-T cells for T cell acute lymphoblastic leukemia (T-ALL) treatment. Feasibility was evaluated systematically, revealing that blocking the CD7 antigen with an antibody effectively blocked CD7-derived fratricide, increased the expansion rate, reduced the proportion of regulatory T (Treg) cells, maintained the stem cell-like characteristics of T cells, and restored the proportion of the CD8+ T cell population. Ultimately, we obtained anti-CD7 CAR-T cells that were specifically and effectively able to kill CD7 antigen-positive target cells, obviating the need for complex T cell modifications. This approach is safer than previous methods and provides a new, simple, and feasible strategy for clinical immunotherapies targeting CD7-positive malignant tumors.

Chimeric antigen receptors containing the OX40 signalling domain enhance the persistence of T cells even under repeated stimulation with multiple myeloma target cells.

Persistence of CAR-T cell function is associated with relapse rate after CAR-T therapy, while co-stimulatory agents are highly concerned with the persistence of CAR-T cells. In this study, we designed and constructed a series of BCMA-targeting second-generation CAR constructs containing CD28, 41BB, and OX40 molecules, respectively, to identify the costimulatory domains most favorable for persistence. The results of routine in vitro studies showed that OX40-CAR-T and 41BB-CAR-T had similar antitumor effects and were superior to CD28-CAR-T in terms of proliferation and cytotoxicity. Although difficult to distinguish by conventional functional assays, OX40-CAR-T cells exhibited greater proliferation and enhanced immune memory than 41BB-CAR-T cells with the repeated stimulation assay by BCMA-expressing target cells. In vivo studies further demonstrated that OX40-CAR-T cells had stronger proliferative activity than 41BB-CAR-T cells, which was highly consistent with the in vitro antitumor activity and proliferation results. Our study provides for the first time a scientific basis for designing OX40-CAR-T cell therapy to improve relapse in patients with MM after CAR-T treatment.

Emerging role of RNA interference in immune cells engineering and its therapeutic synergism in immunotherapy.

RNAi effectors (e.g. siRNA, shRNA and miRNA) can trigger the silencing of specific genes causing alteration of genomic functions becoming a new therapeutic area for the treatment of infectious diseases, neurodegenerative disorders and cancer. In cancer treatment, RNAi effectors showed potential immunomodulatory actions by down-regulating immuno-suppressive proteins, such as PD-1 and CTLA-4, which restrict immune cell function and present challenges in cancer immunotherapy. Therefore, compared with extracellular targeting by antibodies, RNAi-mediated cell-intrinsic disruption of inhibitory pathways in immune cells could promote an increased anti-tumour immune response. Along with non-viral vectors, DNA-based RNAi strategies might be a more promising method for immunomodulation to silence multiple inhibitory pathways in T cells than immune checkpoint blockade antibodies. Thus, in this review, we discuss diverse RNAi implementation strategies, with recent viral and non-viral mediated RNAi synergism to immunotherapy that augments the anti-tumour immunity. Finally, we provide the current progress of RNAi in clinical pipeline.

Gene Therapy for Hepatocellular Carcinoma Using Adenoviral Vectors Delivering a Gene Encoding IL-17A-Neutralizing Antibody Fragments.

High interleukin 17A (IL-17A) expression in hepatocellular carcinoma (HCC) tissue promotes HCC development. This study explores a method to inhibit HCC growth by neutralizing IL-17A in the HCC microenvironment. A novel type 5 adenoviral vector (Ad5) that carries DNA sequences encoding specific neutralizing IL-17A recombinant antibody fragments was developed in this research. After locally injecting into tumor tissues, the Ad5 transduced into tumor cells. This leads to the expression of the anti-IL-17A recombinant antibody fragments in the HCC tissue and consequently to an inhibition of HCC growth by neutralizing IL-17A. The stability of the antibody fragments was optimized by different structures design. Stable HCC cell lines that secrete IL-17A continuously were constructed, which showed stronger invasion and migration ability than control HCC cell lines. In addition, the enhanced migration and invasion ability were partially reversed by applying the adenoviral vectors. These results suggest that IL-17A might promote HCC growth by enhancing the invasion and migration ability of hepatoma cells. The antibody fragments from Ad5 neutralized IL-17A locally, in turn inhibiting the growth of HCC tumors. In conclusion, the local administration of Ad5 vectors encoding IL-17A-neutralizing antibody fragments provides a new option for HCC immunotherapy.