Methods and Process Optimization for Large-Scale CAR T Expansion Using the G-Rex Cell Culture Platform

Optimized GMP-grade production of non-viral Sleeping Beauty-generated CARCIK cells for enhanced fitness and clinical scalability

BACKGROUND

Strict adherence to GMP guidelines and regulatory compliance is crucial when transitioning from research to clinical-grade production of ATMPs like CAR T cells. The success of CAR T cell therapy in treating hematological malignancies highlights the need for closed or automated systems to ensure quality and efficacy. Recent evidence also suggests that ex vivo culture conditions can significantly impact CAR T cell functionality.

METHODS

We present our optimized methodology for expanding Sleeping Beauty transposon-engineered Chimeric Antigen Receptor-Cytokine-Induced Killer (CARCIK) cells using G-Rex devices and evaluate its impact on CARCIK cell phenotype and T cell fitness.

RESULTS

Building on our previously validated protocol, we introduced key simplifications to optimize the CARCIK differentiation process. Delaying the nucleofection step eliminated the need for feeder cells while maintaining efficient CAR expression and high cell viability. Transitioning from T-flasks to G-Rex bioreactors reduced operator hands-on time from 21 to 28 days to 14-17 days and resulted in a less differentiated CARCIK cell product. Metabolic and transcriptional analyses showed that the novel protocol improves CARCIK cell fitness and in vivo efficacy against B-cell lymphoma. The novel method was validated in Good Manufacturing Practices (GMP) conditions at our two Cell Factories and yielded enough numbers of CARCIK-CD19 cells for clinical use.

CONCLUSIONS

Optimizing non-viral CARCIK cell production using G-Rex bioreactors and refined timing adjustments has streamlined the workflow, enhanced cell fitness, and resulted in a highly effective therapeutic product with demonstrated in vivo efficacy in mice. These improvements reduced manipulation and contamination risks, while optimizing logistics and space efficiency, facilitating allogeneic CARCIK generation for a current phase I/II clinical trial (NCT05869279) in patients with R/R CD19 + non-Hodgkin Lymphoma (B-cell NHL) and Chronic Lymphocytic Leukemia (CLL), confirming the approach's scalability and clinical potential.

Engineering safe anti-CD19-CD28ζ CAR T cells with CD8a hinge domain in serum-free media for adoptive immunotherapy

Background

Despite the curative potential, high cost of manufacturing and the toxicities limits the wider access of Chimeric Antigen Receptor (CAR) T cell therapy in global medicine. CARs are modular synthetic antigen receptors integrating the single-chain variable fragment (scFv) of an immunoglobulin molecule to the TCR signaling. CARs allow HLA independent, T cell mediated destruction of tumor cells independent of tumor associated-HLA downregulation and survive within the patient as 'living drug.' Here we report a safer approach for engineering alpha beta T cells with anti- CD19-CD28ζ CAR using self-inactivating (SIN) lentiviral vectors for adoptive immunotherapy.

Method

αβ T cells from the peripheral blood (PB) were lentivirally transduced with CAR construct containing hinge domain from CD8α, transmembrane and co-stimulatory domain from CD28 along with signaling domain from CD3ζ and driven by human UBC promoter. The cells were pre-stimulated through CD3/CD28 beads before lentiviral transduction. Transduction efficiency, fold expansion and phenotype were monitored for the CAR T cells expanded for 10-12 days. The antigen-specific tumor-killing capacity of CD19 CAR T cells was assessed against a standard CD19 expressing NALM6 cell lines with a flow cytometry-based assay optimized in the lab.

Results and conclusion

We have generated high titer lentiviral vectors of CAR with a titer of 9.85 ± 2.2×107 TU/ml (mean ± SEM; n=9) generating a transduction efficiency of 27.57 ± 2.4%. (n=7) at an MOI of 10 in total T cells. The product got higher CD8+ to CD4+ CAR T cell ratio with preponderance of an effector memory phenotype on day 07 and day 12. The CAR-T cells expanded (148.4 ± 29 fold; n=7) in serum free media with very high viability (87.8 ± 2.2%; n=7) on day 12. The antitumor functions of CD19 CAR T cells as gauged against percentage lysis of NALM6 cells at a 1:1 ratio is 27.68 ± 6.87% drawing up to the release criteria. CAR T cells produced IFNγ (11.23 ± 1.5%; n=6) and degranulation marker CD107α (34.82 ± 2.08%; n=5) in an antigen-specific manner. Furthermore, the sequences of WPRE, GFP, and P2A were removed from the CAR construct to enhance safety. These CAR T cells expanded up to 21.7 ± 5.53 fold with 82.7±5.43% viability (n=4).

Conclusion

We have generated, validated, and characterized a reproducible indigenous workflow for generating anti-CD19 CAR T cells in vitro. This approach can be used for targeting cancer and autoimmune diseases in which CD19+ B lineage cells cause host damage.

Rapid manufacture of low-seed CAR-T cells in a GMP-grade hollow-fiber bioreactor platform

Both quality of product and rapidity of manufacture are critical parameters if ex vivo manufacturing of autologous chimeric antigen receptor T cell (CAR-T) therapies is to reach its full potential. The Quantum Flex Cell Expansion System from Terumo Blood and Cell Technologies (Terumo BCT), a hollow-fiber bioreactor platform, is one of several cell expansion systems available to cell and gene therapy manufacturers to generate such cells in a GMP-compliant manner. In this study, the dynamic range of the Quantum Flex platform to expand CD19 CAR-T cells from variable quantities of starting material was investigated. Reflecting the industry's utilization of contract development manufacturing organizations (CDMOs) for accelerating clinical timelines, Terumo Blood and Cell Technologies performed a technology transfer of application protocols for study execution. Four different amounts of starting material (1, 3, 6 and 15 million cells) were expanded on Quantum Flex, using a unique donor's cells for each run. In this study, CAR-T cells were created using commercially obtained T cells and an anti-CD19 CAR-T lentiviral construct. The resultant heterogenous cell populations were expanded for 7 days in the functionally closed bioreactor platform. Expansion kinetics for all 4 starting material amounts were remarkedly similar, resulting in a 150- to 200-fold increase in cell numbers. This allowed for a study maximum of 2.6 billion cells from loading 15 million cells. Viability remained high throughout the expansion process with >93% for all 4 donors at harvest. To complete the manufacturing cycle, the automated and functionally closed Finia Fill and Finish System (Terumo Blood and Cell Technologies, Lakewood, CO) was used to formulate the cells for cryopreservation. Postprocedure analysis for potency and cytotoxicity demonstrated the production of efficacious cells. With this range of starting numbers, the platform is relevant to adult, pediatric and compassionate CAR-T expansion dosing. Today, several platforms are available to achieve sufficient cell yields for therapeutic applications of CAR-T, and awareness of the capabilities, pros and cons of each platform is critical to drive progress.

A high-density microfluidic bioreactor for the automated manufacturing of CAR T cells

The manufacturing of autologous chimaeric antigen receptor (CAR) T cells largely relies either on fed-batch and manual processes that often lack environmental monitoring and control or on bioreactors that cannot be easily scaled out to meet patient demands. Here we show that human primary T cells can be activated, transduced and expanded to high densities in a 2 ml automated closed-system microfluidic bioreactor to produce viable anti-CD19 CAR T cells (specifically, more than 60 million CAR T cells from donor cells derived from patients with lymphoma and more than 200 million CAR T cells from healthy donors). The in vitro secretion of cytokines, the short-term cytotoxic activity and the long-term persistence and proliferation of the cell products, as well as their in vivo anti-leukaemic activity, were comparable to those of T cells produced in a gas-permeable well. The manufacturing-process intensification enabled by the miniaturized perfusable bioreactor may facilitate the analysis of the growth and metabolic states of CAR T cells during ex vivo culture, the high-throughput optimization of cell-manufacturing processes and the scale out of cell-therapy manufacturing.

Advances in manufacturing chimeric antigen receptor immune cell therapies

Biomedical research has witnessed significant strides in manufacturing chimeric antigen receptor T cell (CAR-T) therapies, marking a transformative era in cellular immunotherapy. Nevertheless, existing manufacturing methods for autologous cell therapies still pose several challenges related to cost, immune cell source, safety risks, and scalability. These challenges have motivated recent efforts to optimize process development and manufacturing for cell therapies using automated closed-system bioreactors and models created using artificial intelligence. Simultaneously, non-viral gene transfer methods like mRNA, CRISPR genome editing, and transposons are being applied to engineer T cells and other immune cells like macrophages and natural killer cells. Alternative sources of primary immune cells and stem cells are being developed to generate universal, allogeneic therapies, signaling a shift away from the current autologous paradigm. These multifaceted innovations in manufacturing underscore a collective effort to propel this therapeutic approach toward broader clinical adoption and improved patient outcomes in the evolving landscape of cancer treatment. Here, we review current CAR immune cell manufacturing strategies and highlight recent advancements in cell therapy scale-up, automation, process development, and engineering.

CAR-T cell expansion platforms yield distinct T cell differentiation states

With investigators looking to expand engineered T cell therapies such as CAR-T to new tumor targets and patient populations, a variety of cell manufacturing platforms have been developed to scale manufacturing capacity using closed and/or automated systems. Such platforms are particularly useful for solid tumor targets, which typically require higher CAR-T cell doses. Although T cell phenotype and function are key attributes that often correlate with therapeutic efficacy, how manufacturing platforms influence the final CAR-T cell product is currently unknown. We compared 4 commonly used T cell manufacturing platforms (CliniMACS Prodigy, Xuri W25 rocking platform, G-Rex gas-permeable bioreactor, static bag culture) using identical media, stimulation, culture length, and donor starting material. Selected CD4+CD8+ cells were transduced with lentiviral vector incorporating a CAR targeting FGFR4, a promising target for pediatric sarcoma. We observed significant differences in overall expansion over the 14-day culture; bag cultures had the highest capacity for expansion while the Prodigy had the lowest (481-fold versus 84-fold, respectively). Strikingly, we also observed considerable differences in the phenotype of the final product, with the Prodigy significantly enriched for CCR7+CD45RA+ naïve/stem central memory (Tn/scm)-like cells at 46% compared to bag and G-Rex with 16% and 13%, respectively. Gene expression analysis also showed that Prodigy CAR-Ts are more naïve, less cytotoxic and less exhausted than bag, G-Rex, and Xuri CAR-Ts, and pointed to differences in cell metabolism that were confirmed via metabolic assays. We hypothesized that dissolved oxygen level, which decreased substantially during the final 3 days of the Prodigy culture, may contribute to the observed differences in T cell phenotype. By culturing bag and G-Rex cultures in 1% O2 from day 5 onward, we could generate >60% Tn/scm-like cells, with longer time in hypoxia correlating with a higher percentage of Tn/scm-like cells. Intriguingly, our results suggest that oxygenation is responsible, at least in part, for observed differences in T cell phenotype among bioreactors and suggest hypoxic culture as a potential strategy prevent T cell differentiation during expansion. Ultimately, our study demonstrates that selection of bioreactor system may have profound effects not only on the capacity for expansion, but also on the differentiation state of the resulting CAR-T cells.

Expansion and Retroviral Transduction of Primary Murine T Cells for CAR T-Cell Therapy

The development of chimeric antigen receptor (CAR) T cells has been a revolutionary technology for the treatment of relapsed and refractory leukemias and lymphomas. The synthetic CAR molecule redirects T cell function toward tumor surface-expressed antigens through a single-chain variable fragment (scFv) fused to CD3z and intracellular costimulatory domains. Here, we describe a protocol for the generation of CAR T cells using primary mouse T cells and a gammaretroviral vector encoding a CAR transgene. This protocol outlines several transduction and expansion methods based on the use of two transduction enhancers, RetroNectin® and Vectofusin®-1, and cell culture systems such as conventional plates or G-Rex® devices.

Roles and mechanisms of umbilical cord mesenchymal stem cells in the treatment of diabetic foot: A review of preclinical and clinical studies

AIMS

Growing preclinical and clinical evidence has suggested the potential method of umbilical cord mesenchymal stem cell (UCMSC) therapy for diabetic foot. Thus, the authors provided an outline of the application of UCMSCs in the treatment of diabetic foot and further summarized the roles and mechanisms of this therapy.

DATA SYNTHESIS

With no time limitations, the authors searched the Web of Science, Cochrane Central Register of Controlled Trials, and PubMed (MEDLINE) databases. 14 studies were included, including 9 preclinical experiments and 5 clinical trials (3 RCTs and 2 single-arm trials).

CONCLUSIONS

The UCMSCs are of great efficacy and safety, and function mainly by reducing inflammation, regulating immunity, promoting growth factors, and enhancing the functions of vascular endothelial cells, fibroblasts, and keratinocytes. As a result, ulcer healing-related biological processes ensue, which finally lead to diabetic foot ulcer healing and clinical symptom improvement. UCMSC treatment enhances diabetic foot ulcer healing and has a safety profile. They function mainly by modulating immunity, promoting growth factor secretion, and enhancing cellular functions. More well-designed preclinical and clinical studies are needed to provide the most optimal protocol, the comprehensive molecular mechanisms, as well as to further evaluate the efficiency and safety profile of UCMSC treatment in diabetic foot patients.

How can Cytokine-induced killer cells overcome CAR-T cell limits

The successful treatment of patients affected by B-cell malignancies with Chimeric Antigen Receptor (CAR)-T cells represented a breakthrough in the field of adoptive cell therapy (ACT). However, CAR-T therapy is not an option for every patient, and several needs remain unmet. In particular, the production of CAR-T cells is expensive, labor-intensive and logistically challenging; additionally, the toxicities deriving from CAR-T cells infusion, such as cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), have been documented extensively. Alternative cellular therapy products such as Cytokine-induced killer (CIK) cells have the potential to overcome some of these obstacles. CIK cells are a heterogeneous population of polyclonal CD3+CD56+ T cells with phenotypic and functional properties of NK cells. CIK cell cytotoxicity is exerted in a major histocompatibility complex (MHC)-unrestricted manner through the engagement of natural killer group 2 member D (NKG2D) molecules, against a wide range of hematological and solid tumors without the need for prior antigen exposure or priming. The foremost potential of CIK cells lies in the very limited ability to induce graft-versus-host disease (GvHD) reactions in the allogeneic setting. CIK cells are produced with a simple and extremely efficient expansion protocol, which leads to a massive expansion of effector cells and requires a lower financial commitment compared to CAR-T cells. Indeed, CAR-T manufacturing involves the engineering with expensive GMP-grade viral vectors in centralized manufacturing facilities, whereas CIK cell production is successfully performed in local academic GMP facilities, and CIK cell treatment is now licensed in many countries. Moreover, the toxicities observed for CAR-T cells are not present in CIK cell-treated patients, thus further reducing the costs associated with hospitalization and post-infusion monitoring of patients, and ultimately encouraging the delivery of cell therapies in the outpatient setting. This review aims to give an overview of the limitations of CAR-T cell therapy and outline how the use of CIK cells could overcome such drawbacks thanks to their unique features. We highlight the undeniable advantages of using CIK cells as a therapeutic product, underlying the opportunity for further research on the topic.

Manufacture and Quality Control of Human Umbilical Cord-Derived Mesenchymal Stem Cell Sheets for Clinical Use

Human umbilical cord-derived mesenchymal stem cell (UC−MSC) sheets have attracted much attention in cell therapy. However, the culture media and coating matrix used for the preparation of UC−MSC sheets have not been safe enough to comply with current clinical drug standards. Moreover, the UC−MSC sheet preservation systems developed before did not comply with Good Manufacturing Practice (GMP) regulations. In this study, the culture medium and coating matrix were developed for UC−MSC sheet production to comply with clinical drug standards. Additionally, the GMP-compliant preservation solution and method for the UC−MSC sheet were developed. Then, quality standards of the UC−MSC sheet were formulated according to national and international regulations for drugs. Finally, the production process of UC−MSC sheets on a large scale was standardized, and three batches of trial production were conducted and tested to meet the established quality standards. This research provides the possibility for clinical trials of UC−MSC sheet products in the development stage of new drugs and lays the foundation for industrial large-scale production after the new drug is launched.

Influence of Culture Conditions on Ex Vivo Expansion of T Lymphocytes and Their Function for Therapy: Current Insights and Open Questions

Ex vivo expansion of T lymphocytes is a central process in the generation of cellular therapies targeted at tumors and other disease-relevant structures, which currently cannot be reached by established pharmaceuticals. The influence of culture conditions on T cell functions is, however, incompletely understood. In clinical applications of ex vivo expanded T cells, so far, a relatively classical standard cell culture methodology has been established. The expanded cells have been characterized in both preclinical models and clinical studies mainly using a therapeutic endpoint, for example antitumor response and cytotoxic function against cellular targets, whereas the influence of manipulations of T cells ex vivo including transduction and culture expansion has been studied to a much lesser detail, or in many contexts remains unknown. This includes the circulation behavior of expanded T cells after intravenous application, their intracellular metabolism and signal transduction, and their cytoskeletal (re)organization or their adhesion, migration, and subsequent intra-tissue differentiation. This review aims to provide an overview of established T cell expansion methodologies and address unanswered questions relating in vivo interaction of ex vivo expanded T cells for cellular therapy.

Impact of Manufacturing Procedures on CAR T Cell Functionality

The field of chimeric antigen receptor (CAR) modified T cell therapy has rapidly expanded in the past few decades. As of today, there are six CAR T cell products that have been approved by the FDA: KYMRIAH (tisagenlecleucel, CD19 CAR T cells), YESCARTA (axicabtagene ciloleucel, CD19 CAR T cells), TECARTUS (brexucabtagene autoleucel, CD19 CAR T cells), BREYANZI (lisocabtagene maraleucel, CD19 CAR T cells), ABECMA (idecabtagene vicleucel, BCMA CAR T cells) and CARVYKTI (ciltacabtagene autoleucel, BCMA CAR T cells). With this clinical success, CAR T cell therapy has become one of the most promising treatment options to combat cancers. Current research efforts focus on further potentiating its efficacy in non-responding patients and solid tumor settings. To achieve this, recent evidence suggested that, apart from developing next-generation CAR T cells with additional genetic modifications, ex vivo culture conditions could significantly impact CAR T cell functionality - an often overlooked aspect during clinical translation. In this review, we focus on the ex vivo manufacturing process for CAR T cells and discuss how it impacts CAR T cell function.

Scalable Manufacturing of CAR T cells for Cancer Immunotherapy

As of April 2021, there are five commercially available chimeric antigen receptor (CAR) T cell therapies for hematological malignancies. With the current transition of CAR T cell manufacturing from academia to industry, there is a shift toward Good Manufacturing Practice (GMP)-compliant closed and automated systems to ensure reproducibility and to meet the increased demand for cancer patients. In this review we describe current CAR T cells clinical manufacturing models and discuss emerging technological advances that embrace scaling and production optimization. We summarize measures being used to shorten CAR T-cell manufacturing times and highlight regulatory challenges to scaling production for clinical use.

Statement of Significance ∣

As the demand for CAR T cell cancer therapy increases, several closed and automated production platforms are being deployed, and others are in development.This review provides a critical appraisal of these technologies that can be leveraged to scale and optimize the production of next generation CAR T cells.

Lymphocyte expansion in bioreactors: upgrading adoptive cell therapy

Bioreactors are essential tools for the development of efficient and high-quality cell therapy products. However, their application is far from full potential, holding several challenges when reconciling the complex biology of the cells to be expanded with the need for a manufacturing process that is able to control cell growth and functionality towards therapy affordability and opportunity. In this review, we discuss and compare current bioreactor technologies by performing a systematic analysis of the published data on automated lymphocyte expansion for adoptive cell therapy. We propose a set of requirements for bioreactor design and identify trends on the applicability of these technologies, highlighting the specific challenges and major advancements for each one of the current approaches of expansion along with the opportunities that lie in process intensification. We conclude on the necessity to develop targeted solutions specially tailored for the specific stimulation, supplementation and micro-environmental needs of lymphocytes’ cultures, and the benefit of applying knowledge-based tools for process control and predictability.

Immunotherapy Deriving from CAR-T Cell Treatment in Autoimmune Diseases

Chimeric antigen receptor T (CAR-T) cells are T cells engineered to express specific synthetic antigen receptors that can recognize antigens expressed by tumor cells, which after the binding of these antigens to the receptors are eliminated, and have been adopted to treat several kinds of malignancies. Autoimmune diseases (AIDs), a class of chronic disease conditions, can be broadly separated into autoantibody-mediated and T cell-mediated diseases. Treatments for AIDs are focused on restoring immune tolerance. However, current treatments have little effect on immune tolerance inverse; even the molecular target biologics like anti-TNFα inhibitors can only mildly restore immune balance. By using the idea of CAR-T cell treatment in tumors, CAR-T cell-derived immunotherapies, chimeric autoantibody receptor T (CAAR-T) cells, and CAR regulatory T (CAR-T) cells bring new hope of treatment choice for AIDs.