A lymphodepleted non-human primate model for the assessment of acute on-target and off-tumor toxicity of human chimeric antigen receptor-T cells

In vivo tracking of ex vivo generated 89 Zr-oxine labeled plasma cells by PET in a non-human primate model

B cells are an attractive platform for engineering to produce protein-based biologics absent in genetic disorders, and potentially for the treatment of metabolic diseases and cancer. As part of pre-clinical development of B cell medicines, we demonstrate a method to collect, ex vivo expand, differentiate, radioactively label, and track adoptively transferred non-human primate (NHP) B cells. These cells underwent 10- to 15-fold expansion, initiated IgG class switching, and differentiated into antibody secreting cells. Zirconium-89-oxine labeled cells were infused into autologous donors without any preconditioning and tracked by PET/CT imaging. Within 24 hours of infusion, 20% of the initial dose homed to the bone marrow and spleen and distributed stably and equally between the two. Interestingly, approximately half of the dose homed to the liver. Image analysis of the bone marrow demonstrated inhomogeneous distribution of the cells. The subjects experienced no clinically significant side effects or laboratory abnormalities. A second infusion of B cells into one of the subjects resulted in an almost identical distribution of cells, suggesting a non-limiting engraftment niche and feasibility of repeated infusions. This work supports the NHP as a valuable model to assess the potential of B cell medicines as potential treatment for human diseases.

Progress in developing microphysiological systems for biological product assessment

Microphysiological systems (MPS), also known as miniaturized physiological environments, have been engineered to create and study functional tissue units capable of replicating organ-level responses in specific contexts. The MPS has the potential to provide insights about the safety, characterization, and effectiveness of medical products that are different and complementary to insights gained from traditional testing systems, which can help facilitate the transition of potential medical products from preclinical phases to clinical trials, and eventually to market. While many MPS are versatile and can be used in various applications, most of the current applications have primarily focused on drug discovery and testing. Yet, there is a limited amount of research available that demonstrates the use of MPS in assessing biological products such as cellular and gene therapies. This review paper aims to address this gap by discussing recent technical advancements in MPS and their potential for assessing biological products. We further discuss the challenges and considerations involved in successful translation of MPS into mainstream product testing.

Ligand-based, piggyBac-engineered CAR-T cells targeting EGFR are safe and effective against non-small cell lung cancers

Epidermal growth factor receptor (EGFR) is overexpressed in various cancers, including non-small cell lung cancer (NSCLC), and in some somatic cells at a limited level, rendering it an attractive antitumor target. In this study, we engineered chimeric antigen receptor (CAR)-T cells using the piggyBac transposon system, autologous artificial antigen-presenting cells, and natural ligands of EGFR. We showed that this approach yielded CAR-T cells with favorable phenotypes and CAR positivity. They exhibited potent antitumor activity against NSCLC both in vitro and in vivo. When administered to tumor-bearing mice and non-tumor-bearing cynomolgus macaques, they did not elicit toxicity despite their cross-reactivity to both murine and simian EGFRs. In total we tested three ligands and found that the CAR candidate with the highest affinity consistently displayed greater potency without adverse events. Taken together, our results demonstrate the feasibility and safety of targeting EGFR-expressing NSCLCs using ligand-based, piggyBac-engineered CAR-T cells. Our data also show that lowering the affinity of CAR molecules is not always beneficial.

piggyBac-transposon-mediated CAR-T cells for the treatment of hematological and solid malignancies

Since the introduction of the use of chimeric antigen receptor T-cell therapy (CAR-T therapy) dramatically changed the therapeutic strategy for B cell tumors, various CAR-T cell products have been developed and applied to myeloid and solid tumors. Although viral vectors have been widely used to produce genetically engineered T cells, advances in genetic engineering have led to the development of methods for producing non-viral, gene-modified CAR-T cells. Recent progress has revealed that non-viral CAR-T cells have a significant impact not only on the simplicity of the production process and the accessibility of non-viral vectors but also on the function of the cells themselves. In this review, we focus on piggyBac-transposon-based CAR-T cells among non-viral, gene-modified CAR-T cells and discuss their characteristics, preclinical development, and recent clinical applications.

Evaluation of CAR-T Cells' Cytotoxicity against Modified Solid Tumor Cell Lines

In recent years, adoptive cell therapy has gained a new perspective of application due to the development of technologies and the successful clinical use of CAR-T cells for the treatment of patients with malignant B-cell neoplasms. However, the efficacy of CAR-T therapy against solid tumor remains a major scientific and clinical challenge. In this work, we evaluated the cytotoxicity of 2nd generation CAR-T cells against modified solid tumors cell lines-lung adenocarcinoma cell line H522, prostate carcinoma PC-3M, breast carcinoma MDA-MB-231, and epidermoid carcinoma A431 cell lines transduced with lentiviruses encoding red fluorescent protein Katushka2S and the CD19 antigen. A correlation was demonstrated between an increase in the secretion of proinflammatory cytokines and a decrease in the confluence of tumor cells' monolayer. The proposed approach can potentially be applied to preliminarily assess CAR-T cell efficacy for the treatment of solid tumors and estimate the risks of developing cytokine release syndrome.

CAR-Based Immunotherapy of Solid Tumours-A Survey of the Emerging Targets

Immunotherapy with CAR T-cells has revolutionised the treatment of B-cell and plasma cell-derived cancers. However, solid tumours present a much greater challenge for treatment using CAR-engineered immune cells. In a partner review, we have surveyed data generated in clinical trials in which patients with solid tumours that expressed any of 30 discrete targets were treated with CAR-based immunotherapy. That exercise confirms that efficacy of this approach falls well behind that seen in haematological malignancies, while significant toxic events have also been reported. Here, we consider approximately 60 additional candidates for which such clinical data are not available yet, but where pre-clinical data have provided support for their advancement to clinical evaluation as CAR target antigens.

Applying a Clinical Lens to Animal Models of CAR-T Cell Therapies

Chimeric antigen receptor (CAR)-T cells have emerged as a promising treatment modality for various hematologic and solid malignancies over the past decade. Animal models remain the cornerstone of pre-clinical evaluation of human CAR-T cell products and are generally required by regulatory agencies prior to clinical translation. However, pharmacokinetics and pharmacodynamics of adoptively transferred T cells are dependent on various recipient factors, posing challenges for accurately predicting human engineered T cell behavior in non-human animal models. For example, murine xenograft models did not forecast now well-established cytokine-driven systemic toxicities of CAR-T cells seen in humans, highlighting the limitations of animal models that do not perfectly recapitulate complex human immune systems. Understanding the concordance as well as discrepancies between existing pre-clinical animal data and human clinical experiences, along with established advantages and limitations of each model, will facilitate investigators’ ability to appropriately select and design animal models for optimal evaluation of future CAR-T cell products. We summarize the current state of animal models in this field, and the advantages and disadvantages of each approach depending on the pre-clinical questions being asked.

Time to evolve: predicting engineered T cell-associated toxicity with next-generation models

Despite promising clinical results in a small subset of malignancies, therapies based on engineered chimeric antigen receptor and T-cell receptor T cells are associated with serious adverse events, including cytokine release syndrome and neurotoxicity. These toxicities are sometimes so severe that they significantly hinder the implementation of this therapeutic strategy. For a long time, existing preclinical models failed to predict severe toxicities seen in human clinical trials after engineered T-cell infusion. However, in recent years, there has been a concerted effort to develop models, including humanized mouse models, which can better recapitulate toxicities observed in patients. The Accelerating Development and Improving Access to CAR and TCR-engineered T cell therapy (T2EVOLVE) consortium is a public–private partnership directed at accelerating the preclinical development and increasing access to engineered T-cell therapy for patients with cancer. A key ambition in T2EVOLVE is to design new models and tools with higher predictive value for clinical safety and efficacy, in order to improve and accelerate the selection of lead T-cell products for clinical translation. Herein, we review existing preclinical models that are used to test the safety of engineered T cells. We will also highlight limitations of these models and propose potential measures to improve them.

Preclinical pharmacology modeling of chimeric antigen receptor T therapies

Chimeric antigen receptor (CAR) T cells have largely been successful in treating hematological malignancies in the clinic but have not been as effective in treating solid tumors, in part, owing to poor access and the immunosuppressive tumor microenvironment. In addition, CAR-T therapy can cause potentially life-threatening side effects, including cytokine release syndrome and neurotoxicity. Current preclinical testing of CAR-T therapy efficacy is typically performed in mouse tumor models, which often fails to predict toxicity. Recent developments in humanized models and transgenic mice as well as in vitro three-dimensional organoids in early development and nonhuman primate models are being adopted for CAR-T cell efficacy and toxicity assessment. However, because no single model perfectly recapitulates the human immune system and tumor microenvironment, careful model selection based on their respective pros and cons is crucial for adequate evaluation of different CAR-T treatments, so that their clinical development can be better supported.