Optimizing the production of suspension cells using the G-Rex "M" series

Scalable process development of NK and CAR-NK expansion in a closed bioreactor

Production of large amounts of functional NK and CAR-NK cells represents one of the bottlenecks for NK-based immunotherapy. In this study, we developed a large-scale, reliable, and practicable NK and CAR-NK production using G-Rex 100M bioreactors, which depend on a gas-permeable membrane technology. This system holds large volumes of medium with enhanced oxygen delivery, creating conditions conducive to large-scale PBNK and CAR-NK expansions for cancer therapy. Both peripheral blood NK cells (PBNKs) and CAR-NKs expanded in these bioreactors retained similar immunophenotypes and exhibited comparable cytotoxicity towards hepatocellular carcinoma (HCC) cells akin to that of NK and CAR-NK cells expanded in G-Rex 6 well bioreactors. Importantly, cryopreservation minimally affected the cytotoxicity of NK cells expanded using the G-Rex 100M bioreactors, establishing a robust platform for scaled-up NK and CAR-NK cell production. This method is promising for the development of "off-the-shelf" NK cells, supporting the future clinical implementation of NK cell immunotherapy.

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.

A quality-by-design approach to improve process understanding and optimise the production and quality of CAR-T cells in automated stirred-tank bioreactors

Ex vivo genetically-modified cellular immunotherapies, such as chimeric antigen receptor T cell (CAR-T) therapies, have generated significant clinical and commercial outcomes due to their unparalleled response rates against relapsed and refractory blood cancers. However, the development and scalable manufacture of these novel therapies remains challenging and further process understanding and optimisation is required to improve product quality and yield. In this study, we employ a quality-by-design (QbD) approach to systematically investigate the impact of critical process parameters (CPPs) during the expansion step on the critical quality attributes (CQAs) of CAR-T cells. Utilising the design of experiments (DOE) methodology, we investigated the impact of multiple CPPs, such as number of activations, culture seeding density, seed train time, and IL-2 concentration, on CAR-T CQAs including, cell yield, viability, metabolism, immunophenotype, T cell differentiation, exhaustion and CAR expression. Initial studies undertaken in G-Rex® 24 multi-well plates demonstrated that the combination of a single activation step and a shorter, 3-day, seed train resulted in significant CAR-T yield and quality improvements, specifically a 3-fold increase in cell yield, a 30% reduction in exhaustion marker expression and more efficient metabolism when compared to a process involving 2 activation steps and a 7-day seed train. Similar findings were observed when the CPPs identified in the G-Rex® multi-well plates studies were translated to a larger-scale automated, controlled stirred-tank bioreactor (Ambr® 250 High Throughput) process. The single activation step and reduced seed train time resulted in a similar, significant improvement in CAR-T CQAs including cell yield, quality and metabolism in the Ambr® 250 High Throughput bioreactor, thereby validating the findings of the small-scale studies and resulting in significant process understanding and improvements. This study provides a methodology for the systematic investigation of CAR-T CPPs and the findings demonstrate the scope and impact of enhanced process understanding for improved CAR-T production.

A scalable human islet 3D-culture platform maintains cell mass and function long-term for transplantation

Present-day islet culture methods provide short-term maintenance of cell viability and function, limiting access to islet transplantation. Attempts to lengthen culture intervals remain unsuccessful. A new method was developed to permit the long-term culture of islets. Human islets were embedded in polysaccharide 3D-hydrogel in cell culture inserts or gas-permeable chambers with serum-free CMRL 1066 supplemented media for up to 8 weeks. The long-term cultured islets maintained better morphology, cell mass, and viability at 4 weeks than islets in conventional suspension culture. In fact, islets cultured in the 3D-hydrogel retained β cell mass and function on par with freshly isolated islets in vitro and, when transplanted into diabetic mice, restored glucose balance similar to fresh islets. Using gas-permeable chambers, the 3D-hydrogel culture method was scaled up over 10-fold and maintained islet viability and function, although the cell mass recovery rate was 50%. Additional optimization of scale-up methods continues. If successful, this technology could afford flexibility and expand access to islet transplantation, especially single-donor islet-after-kidney transplantation.

Engineering Challenges and Opportunities in Autologous Cellular Cancer Immunotherapy

The use of a patient's own immune or tumor cells, manipulated ex vivo, enables Ag- or patient-specific immunotherapy. Despite some clinical successes, there remain significant barriers to efficacy, broad patient population applicability, and safety. Immunotherapies that target specific tumor Ags, such as chimeric Ag receptor T cells and some dendritic cell vaccines, can mount robust immune responses against immunodominant Ags, but evolving tumor heterogeneity and antigenic downregulation can drive resistance. In contrast, whole tumor cell vaccines and tumor lysate-loaded dendritic cell vaccines target the patient's unique tumor antigenic repertoire without prior neoantigen selection; however, efficacy can be weak when lower-affinity clones dominate the T cell pool. Chimeric Ag receptor T cell and tumor-infiltrating lymphocyte therapies additionally face challenges related to genetic modification, T cell exhaustion, and immunotoxicity. In this review, we highlight some engineering approaches and opportunities to these challenges among four classes of autologous cell therapies.

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.

Short-term function and immune-protection of microencapsulated adult porcine islets with alginate incorporating CXCL12 in healthy and diabetic non-human primates without systemic immune suppression: A pilot study

Replacement of insulin-producing pancreatic beta-cells by islet transplantation offers a functional cure for type-1 diabetes (T1D). We recently demonstrated that a clinical grade alginate micro-encapsulant incorporating the immune-repellent chemokine and pro-survival factor CXCL12 could protect and sustain the integrity and function of autologous islets in healthy non-human primates (NHPs) without systemic immune suppression. In this pilot study, we examined the impact of the CXCL12 micro encapsulant on the function and inflammatory and immune responses of xenogeneic islets transplanted into the omental tissue bilayer sac (OB; n = 4) and diabetic (n = 1) NHPs. Changes in the expression of cytokines after implantation were limited to 2-6-fold changes in blood, most of which did not persist over the first 4 weeks after implantation. Flow cytometry of PBMCs following transplantation showed minimal changes in IFNγ or TNFα expression on xenoantigen-specific CD4+  or CD8+  T cells compared to unstimulated cells, and these occurred mainly in the first 4 weeks. Microbeads were readily retrievable for assessment at day 90 and day 180 and at retrieval were without microscopic signs of degradation or foreign body responses (FBR). In vitro and immunohistochemistry studies of explanted microbeads indicated the presence of functional xenogeneic islets at day 30 post transplantation in all biopsied NHPs. These results from a small pilot study revealed that CXCL12-microencapsulated xenogeneic islets abrogate inflammatory and adaptive immune responses to the xenograft. This work paves the way toward future larger scale studies of the transplantation of alginate microbeads with CXCL12 and porcine or human stem cell-derived beta cells or allogeneic islets into diabetic NHPs without systemic immunosuppression.

Recent Advances in the Development of Bioreactors for Manufacturing of Adoptive Cell Immunotherapies

Harnessing the human immune system as a foundation for therapeutic technologies capable of recognizing and killing tumor cells has been the central objective of anti-cancer immunotherapy. In recent years, there has been an increasing interest in improving the effectiveness and accessibility of this technology to make it widely applicable for adoptive cell therapies (ACTs) such as chimeric antigen receptor T (CAR-T) cells, tumor infiltrating lymphocytes (TILs), dendritic cells (DCs), natural killer (NK) cells, and many other. Automated, scalable, cost-effective, and GMP-compliant bioreactors for production of ACTs are urgently needed. The primary efforts in the field of GMP bioreactors development are focused on closed and fully automated point-of-care (POC) systems. However, their clinical and industrial application has not yet reached full potential, as there are numerous obstacles associated with delicate balancing of the complex and often unpredictable cell biology with the need for precision and full process control. Here we provide a brief overview of the existing and most advanced systems for ACT manufacturing, including cell culture bags, G-Rex flasks, and bioreactors (rocking motion, stirred-flask, stirred-tank, hollow-fiber), as well as semi- and fully-automated closed bioreactor systems.

Impact of cryopreservation on CAR T production and clinical response

Adoptive cell therapy with chimeric antigen receptor (CAR) T cells has become an efficient treatment option for patients with hematological malignancies. FDA approved CAR T products are manufactured in centralized facilities from fresh or frozen leukapheresis and the cryopreserved CAR T infusion product is shipped back to the patient. An increasing number of clinical centers produce CAR T cells on-site, which enables the use of fresh and cryopreserved PBMCs and CAR T cells. Here we determined the effect of cryopreservation on PBMCs and CD19 CAR T cells in a cohort of 118 patients treated with fresh CAR T cells and in several patients head-to-head. Cryopreserved PBMCs, obtained from leukapheresis products, contained less erythrocytes and T cells, but were sufficient to produce CAR T cells for therapy. There was no correlation between the recovery of PBMCs and the transduction efficacy, the number of CAR T cells obtained by the end of the manufacturing process, the in vitro reactivity, or the response rate to CAR T therapy. We could show that CAR T cells cryopreserved during the manufacturing process, stored and resumed expansion at a later time point, yielded sufficient cell numbers for treatment and led to complete remissions. Phenotype analysis including T cell subtypes, chemokine receptor and co-inhibitory/stimulatory molecules, revealed that fresh CAR T cells expressed significantly more TIM-3 and contained less effector T cells in comparison to their frozen counterparts. In addition, fresh CAR T infusion products demonstrated increased in vitro anti-tumor reactivity, however cryopreserved CAR T cells still showed high anti-tumor potency and specificity. The recovery of cryopreserved CAR T cells was similar in responding and non-responding patients. Although fresh CAR T infusion products exhibit higher anti-tumor reactivity, the use of frozen PBMCs as staring material and frozen CAR T infusion products seems a viable option, as frozen products still exhibit high in vitro potency and cryopreservation did not seem to affect the clinical outcome.

Surgical Considerations for Tumor Tissue Procurement to Obtain Tumor-Infiltrating Lymphocytes for Adoptive Cell Therapy

ABSTRACT

Adoptive cell therapy with tumor-infiltrating lymphocytes (TILs), an investigational cellular therapy, has demonstrated antitumor efficacy in patients with advanced solid tumors, including melanoma. Tumor-infiltrating lymphocyte cell therapy involves surgical resection of a patient's tumor, ex vivo TIL expansion under conditions that overcome immunosuppressive responses elicited by the tumor and the tumor microenvironment, administration of a lymphodepleting regimen, and infusion of the final TIL cell therapy product back into the patient followed by interleukin 2 administration to support T-cell activity. The surgeon plays a central role in patient identification and tumor selection-steps that are critical for successful outcomes of TIL cell therapy. Commercialization of TIL cell therapy and its broader access to patients will require education and collaboration among surgeons, oncologists, and cellular therapists. This review highlights the unique role that surgeons will play in the implementation of TIL cell therapy and serves as a contemporary report of best practices for patient selection and tumor resection methods.

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.

Process Development for Adoptive Cell Therapy in Academia: A Pipeline for Clinical-Scale Manufacturing of Multiple TCR-T Cell Products

Cellular immunotherapies based on T cell receptor (TCR) transfer are promising approaches for the treatment of cancer and chronic viral infections. The discovery of novel receptors is expanding considerably; however, the clinical development of TCR-T cell therapies still lags. Here we provide a pipeline for process development and clinical-scale manufacturing of TCR-T cells in academia. We utilized two TCRs specific for hepatitis C virus (HCV) as models because of their marked differences in avidity and functional profile in TCR-redirected cells. With our clinical-scale pipeline, we reproduced the functional profile associated with each TCR. Moreover, the two TCR-T cell products demonstrated similar yield, purity, transduction efficiency as well as phenotype. The TCR-T cell products had a highly reproducible yield of over 1.4 × 10⁹ cells, with an average viability of 93%; 97.8–99% of cells were CD3+, of which 47.66 ± 2.02% were CD8+ T cells; the phenotype was markedly associated with central memory (CD62L+CD45RO+) for CD4+ (93.70 ± 5.23%) and CD8+ (94.26 ± 4.04%). The functional assessments in 2D and 3D cell culture assays showed that TCR-T cells mounted a polyfunctional response to the cognate HCV peptide target in tumor cell lines, including killing. Collectively, we report a solid strategy for the efficient large-scale manufacturing of TCR-T cells.

In-situ scalable manufacturing of Epstein-Barr virus-specific T-cells using bioreactor with an expandable culture area (BECA)

The ex-vivo expansion of antigen-specific T-cells for adoptive T-cell immunotherapy requires active interaction between T-cells and antigen-presenting cells therefore culture density and environment become important variables to control. Maintenance of culture density in a static environment is traditionally performed by the expansion of the culture area through splitting of culture from a single vessel into multiple vessels-a highly laborious process. This study aims to validate the use and efficacy of a novel bioreactor, bioreactor with an expandable culture area-dual chamber (BECA-D), that was designed and developed with a cell chamber with expandable culture area (12-108 cm²) and a separate media chamber to allow for in-situ scaling of culture with maintenance of optimum culture density and improved nutrient and gas exchange while minimizing disturbance to the culture. The performance of BECA-D in the culture of Epstein-Barr virus-specific T-cells (EBVSTs) was compared to the 24-well plate. BECA-D had 0.9-9.7 times the average culture yield of the 24-well plates across 5 donor sets. BECA-D was able to maintain the culture environment with relatively stable glucose and lactate levels as the culture expanded. This study concludes that BECA-D can support the culture of ex-vivo EBVSTs with lower manufacturing labour and time requirements compared to the use of the 24-well plate. BECA-D and its adaptation into a closed system with an automated platform (currently being developed) provides cell therapy manufacturers and developers with a closed scale-out solution to producing adoptive cell therapy for clinical use.

Feeder-Cell-Free and Serum-Free Expansion of Natural Killer Cells Using Cloudz Microspheres, G-Rex6M, and Human Platelet Lysate

The versatility of natural killer cells has ignited growing interest in their therapeutic use for cancer and other immunotherapy treatments. However, NK cells compose a small portion of peripheral blood mononuclear cells (5%–20% of PBMCs) and clinical doses require billions of cells. Manufacturing suitable doses of NK cells remains a major challenge for NK immunotherapy. The current standard for expanding NK cells relies on feeder cells and fetal bovine serum to achieve large expansion, but both encounter regulatory concerns. We developed NK Cloudz, a dissolvable polymer-based microsphere platform, as an alternative to a feeder cell approach to expand NK cells. We demonstrated that a combination of NK Cloudz, a G-Rex6M culture vessel, and GMP Human Platelet Lysate expanded NK cells 387 ± 100-fold in 10 days from a PBMC starting population. The NK purity, viability, and cytotoxicity were similar to both a feeder cell protocol and an FBS-based protocol. Additionally, we found no significant differences between FBS and GMP Human Platelet Lysate and concluded that platelet lysate is a good xeno-free alternative to FBS for NK expansion. Overall, we demonstrated a feeder-cell-free and FBS-free protocol that leverages NK Cloudz as a promising step toward a commercial GMP manufacturing method to expand NK cells for therapeutic use.

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.

DL4-μbeads induce T cell lineage differentiation from stem cells in a stromal cell-free system

T cells are pivotal effectors of the immune system and can be harnessed as therapeutics for regenerative medicine and cancer immunotherapy. An unmet challenge in the field is the development of a clinically relevant system that is readily scalable to generate large numbers of T-lineage cells from hematopoietic stem/progenitor cells (HSPCs). Here, we report a stromal cell-free, microbead-based approach that supports the efficient in vitro development of both human progenitor T (proT) cells and T-lineage cells from CD34⁺cells sourced from cord blood, GCSF-mobilized peripheral blood, and pluripotent stem cells (PSCs). DL4-μbeads, along with lymphopoietic cytokines, induce an ordered sequence of differentiation from CD34⁺ cells to CD34⁺CD7⁺CD5⁺ proT cells to CD3⁺αβ T cells. Single-cell RNA sequencing of human PSC-derived proT cells reveals a transcriptional profile similar to the earliest thymocytes found in the embryonic and fetal thymus. Furthermore, the adoptive transfer of CD34⁺CD7⁺ proT cells into immunodeficient mice demonstrates efficient thymic engraftment and functional maturation of peripheral T cells. DL4-μbeads provide a simple and robust platform to both study human T cell development and facilitate the development of engineered T cell therapies from renewable sources.

T cells derived from stem cells can be harnessed for regenerative medicine and cancer immunotherapy, but current technologies limit production and translation. Here, the authors present a serum-free, stromal-cell free DLL4-coated microbead method for the scalable production of T-lineage cells from multiple sources of stem cells.

The National Heart, Lung, and Blood Institute-funded Production Assistance for Cellular Therapies (PACT) program: Eighteen years of cell therapy

The Production Assistance for Cellular Therapies (PACT) Program, is funded and supported by the US Department of Health and Human Services’ National Institutes of Health (NIH) National Heart Lung and Blood Institute (NHLBI) to advance development of somatic cell and genetically modified cell therapeutics in the areas of heart, lung, and blood diseases. The program began in 2003, continued under two competitive renewals, and ended June 2021. PACT has supported cell therapy product manufacturing, investigational new drug enabling preclinical studies, and translational services, and has provided regulatory assistance for candidate cell therapy products that may aid in the repair and regeneration of damaged/diseased cells, tissues, and organs. PACT currently supports the development of novel cell therapies through five cell processing facilities. These facilities offer manufacturing processes, analytical development, technology transfer, process scale‐up, and preclinical development expertise necessary to produce cell therapy products that are compliant with Good Laboratory Practices, current Good Manufacturing Practices, and current Good Tissue Practices regulations. The Emmes Company, LLC, serves as the Coordinating Center and assists with the management and coordination of PACT and its application submission and review process. This paper discusses the impact and accomplishments of the PACT program on the cell therapy field and its evolution over the duration of the program. It highlights the work that has been accomplished and provides a foundation to build future programs with similar goals to advance cellular therapeutics in a coordinated and centralized programmatic manner to support unmet medical needs within NHLBI purview.

Cytometric analysis of T cell phenotype using cytokine profiling for improved manufacturing of an EBV-specific T cell therapy

Adoptive immunotherapy using Epstein–Barr Virus (EBV)‐specific T cells is a potentially curative treatment for patients with EBV‐related malignancies where other clinical options have proved ineffective. We describe improved good manufacturing practice (GMP)‐compliant culture and analysis processes for conventional lymphoblastoid cell line (LCL)‐driven EBV‐specific T cell manufacture, and describe an improved phenotyping approach for analysing T cell products. We optimized the current LCL‐mediated clinical manufacture of EBV‐specific T cells to establish an improved process using xenoprotein‐free GMP‐compliant reagents throughout, and compared resulting products with our previous banked T cell clinical therapy. We assessed effects of changes to LCL:T cell ratio in T cell expansion, and developed a robust flow cytometric marker panel covering T cell memory, activation, differentiation and intracellular cytokine release to characterize T cells more effectively. These data were analysed using a t‐stochastic neighbour embedding (t‐SNE) algorithm. The optimized GMP‐compliant process resulted in reduced cell processing time and improved retention and expansion of central memory T cells. Multi‐parameter flow cytometry determined the optimal protocol for LCL stimulation and expansion of T cells and demonstrated that cytokine profiling using interleukin (IL)‐2, tumour necrosis factor (TNF)‐α and interferon (IFN)‐γ was able to determine the differentiation status of T cells throughout culture and in the final product. We show that fully GMP‐compliant closed‐process culture of LCL‐mediated EBV‐specific T cells is feasible, and profiling of T cells through cytokine expression gives improved characterization of start material, in‐process culture conditions and final product. Visualization of the complex multi‐parameter flow cytometric data can be simplified using t‐SNE analysis.

CAR-T cells: Early successes in blood cancer and challenges in solid tumors

New approaches to cancer immunotherapy have been developed, showing the ability to harness the immune system to treat and eliminate cancer. For many solid tumors, therapy with checkpoint inhibitors has shown promise. For hematologic malignancies, adoptive and engineered cell therapies are being widely developed, using cells such as T lymphocytes, as well as natural killer (NK) cells, dendritic cells, and potentially others. Among these adoptive cell therapies, the most active and advanced therapy involves chimeric antigen receptor (CAR)-T cells, which are T cells in which a chimeric antigen receptor is used to redirect specificity and allow T cell recognition, activation and killing of cancers, such as leukemia and lymphoma. Two autologous CAR-T products have been approved by several health authorities, starting with the U.S. Food and Drug Administration (FDA) in 2017. These products have shown powerful, inducing, long-lasting effects against B cell cancers in many cases. In distinction to the results seen in hematologic malignancies, the field of using CAR-T products against solid tumors is in its infancy. Targeting solid tumors and trafficking CAR-T cells into an immunosuppressive microenvironment are both significant challenges. The goal of this review is to summarize some of the most recent aspects of CAR-T cell design and manufacturing that have led to successes in hematological malignancies, allowing the reader to appreciate the barriers that must be overcome to extend CAR-T therapies to solid tumors successfully.

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.

The Importance of Proper Oxygenation in 3D Culture

Cell culture typically employs inexpensive, disposable plasticware, and standard humidified CO₂/room air incubators (5% CO₂, ∼20% oxygen). These methods have historically proven adequate for the maintenance of viability, function, and proliferation of many cell types, but with broad variation in culture practices. With technological advances it is becoming increasingly clear that cell culture is not a “one size fits all” procedure. Recently, there is a shift toward comprehension of the individual physiological niches of cultured cells. As scale-up production of single cell and 3D aggregates for therapeutic applications has expanded, researchers have focused on understanding the role of many environmental metabolites/forces on cell function and viability. Oxygen, due to its role in cell processes and the requirement for adequate supply to maintain critical energy generation, is one such metabolite gaining increased focus. With the advent of improved sensing technologies and computational predictive modeling, it is becoming evident that parameters such as cell seeding density, culture media height, cellular oxygen consumption rate, and aggregate dimensions should be considered for experimental reproducibility. In this review, we will examine the role of oxygen in 3D cell culture with particular emphasis on primary islets of Langerhans and stem cell-derived insulin-producing SC-β cells, both known for their high metabolic demands. We will implement finite element modeling (FEM) to simulate historical and current culture methods in referenced manuscripts and innovations focusing on oxygen distribution. Our group and others have shown that oxygen plays a key role in proliferation, differentiation, and function of these 3D aggregates. Their culture in plastic consistently results in core regions of hypoxia/anoxia exacerbated by increased media height, aggregate dimensions, and oxygen consumption rates. Static gas permeable systems ameliorate this problem. The use of rotational culture and other dynamic culture systems also have advantages in terms of oxygen supply but come with the caveat that these endocrine aggregates are also exquisitely sensitive to mechanical perturbation. As recent work demonstrates, there is a strong rationale for the use of alternate in vitro systems to maintain physio-normal environments for cell growth and function for better phenotypic approximation of in vivo counterparts.

Objectives, benefits and challenges of bioreactor systems for the clinical-scale expansion of T lymphocyte cells

Cell therapies based on T cell have gathered interest over the last decades for treatment of cancers, becoming recently the most investigated lineage for clinical trials. Although results of adoptive cell therapies are very promising, obtaining large batches of T cell at clinical scale is still challenging nowadays. We propose here a review study focusing on how bioreactor systems could increase expansion rates of T cell culture specifically towards efficient, reliable and reproducible cell therapies. After describing the specificities of T cell culture, in particular activation, phenotypical characterization and cell density considerations, we detail the main objectives of bioreactors in this context, namely scale-up, GMP-compliance and reduced time and costs. Then, we report recent advances on the different classes of bioreactor systems commonly investigated for non-adherent cell expansion, in comparison with the current "gold standard" of T cell culture (flasks and culture bag). Results obtained with hollow fibres, G-Rex® flasks, Wave bioreactor, multiple-step bioreactors, spinner flasks as well as original homemade designs are discussed to highlight advantages and drawbacks in regards to T cells' specificities. Although there is currently no consensus on an optimal bioreactor, overall, most systems reviewed here can improve T cell culture towards faster, easier and/or cheaper protocols. They also offer strong outlooks towards automation, process control and complete closed systems, which could be mandatory developments for a massive clinical breakthrough. However, proper controls are sometimes lacking to conclude clearly on the features leading to the progresses regarding cell expansion, and the field could benefit from process engineering methods, such as quality by design, to perform multi parameters studies and face these challenges.

Cell-Based Therapy Manufacturing in Stirred Suspension Bioreactor: Thoughts for cGMP Compliance

Cell-based therapy (CBT) is attracting much attention to treat incurable diseases. In recent years, several clinical trials have been conducted using human pluripotent stem cells (hPSCs), and other potential therapeutic cells. Various private- and government-funded organizations are investing in finding permanent cures for diseases that are difficult or expensive to treat over a lifespan, such as age-related macular degeneration, Parkinson’s disease, or diabetes, etc. Clinical-grade cell manufacturing requiring current good manufacturing practices (cGMP) has therefore become an important issue to make safe and effective CBT products. Current cell production practices are adopted from conventional antibody or protein production in the pharmaceutical industry, wherein cells are used as a vector to produce the desired products. With CBT, however, the “cells are the final products” and sensitive to physico- chemical parameters and storage conditions anywhere between isolation and patient administration. In addition, the manufacturing of cellular products involves multi-stage processing, including cell isolation, genetic modification, PSC derivation, expansion, differentiation, purification, characterization, cryopreservation, etc. Posing a high risk of product contamination, these can be time- and cost- prohibitive due to maintenance of cGMP. The growing demand of CBT needs integrated manufacturing systems that can provide a more simple and cost-effective platform. Here, we discuss the current methods and limitations of CBT, based upon experience with biologics production. We review current cell manufacturing integration, automation and provide an overview of some important considerations and best cGMP practices. Finally, we propose how multi-stage cell processing can be integrated into a single bioreactor, in order to develop streamlined cGMP-compliant cell processing systems.

Chimeric Antigen Receptor Based Therapy as a Potential Approach in Autoimmune Diseases: How Close Are We to the Treatment?

Despite significant breakthroughs in understanding of immunological and physiological features of autoimmune diseases, there is currently no specific therapeutic option with prolonged remission. Cell-based therapy using engineered-T cells has attracted tremendous attention as a practical treatment for autoimmune diseases. Genetically modified-T cells armed with chimeric antigen receptors (CARs) attack autoreactive immune cells such as B cells or antibody-secreting plasma cells. CARs can further guide the effector and regulatory T cells (Tregs) to the autoimmune milieu to traffic, proliferate, and exert suppressive functions. The genetically modified-T cells with artificial receptors are a promising option to suppress autoimmune manifestation and autoinflammatory events. Interestingly, CAR-T cells are modified to a new chimeric auto-antibody receptor T (CAAR-T) cell. This cell, with its specific-antigen, recognizes and binds to the target autoantibodies expressing autoreactive cells and, subsequently, destroy them. Preclinical studies of CAR-T cells demonstrated satisfactory outcomes against autoimmune diseases. However, the lack of target autoantigens remains one of the pivotal problems in the field of CAR-T cells. CAR-based therapy has to pass several hurdles, including stability, durability, trafficking, safety, effectiveness, manufacturing, and persistence, to enter clinical use. The primary goal of this review was to shed light on CAR-T immunotherapy, CAAR-T cell therapy, and CAR-Treg cell therapy in patients with immune system diseases.

Head-to-head comparison of in-house produced CD19 CAR-T cell in ALL and NHL patients

Background

CD19 chimeric antigen receptor T (CAR-T) cells demonstrate remarkable remission rates in pediatric and adult patients with refractory or relapsed (r/r) acute lymphoblastic leukemia (ALL) and non-Hodgkin's lymphoma (NHL). In 2016, we initiated a clinical trial with in-house produced CD19 CAR-T cells with a CD28 co-stimulatory domain. We analyzed, for the first time, differences in production features and phenotype between ALL and NHL patients.

Methods

Non-cryopreserved CAR-T cells were produced from patients’ peripheral blood mononuclear cells within 9 to 10 days. 93 patients with r/r ALL and NHL were enrolled under the same study. CAR-T cells of ALL and NHL patients were produced simultaneously, allowing the head-to-head comparison.

Results

All patients were heavily pretreated. Three patients dropped out from the study due to clinical deterioration (n=2) or production failure (n=1). Cells of ALL patients (n=37) expanded significantly better and contained more CAR-T cells than of NHL patients (n=53). Young age had a positive impact on the proliferation capacity. The infusion products from ALL patients contained significantly more naïve CAR-T cells and a significantly higher expression of the chemokine receptor CXCR3. PD-1, LAG-3, TIM-3, and CD28 were equally expressed. 100% of ALL patients and 94% of NHL patients received the target dose of 1×10e6 CAR-T/kg. The overall response rate was 84% (30/36) in ALL and 62% (32/52) in NHL. We further compared CAR-T cell infusion products to tumor infiltrating lymphocytes (TIL), another common type of T cell therapy, mainly clinically effective in solid tumors. CAR-T cells contained significantly more naïve T cells and central memory T cells and significantly less CCR5 compared to TIL infusion products.

Conclusions

The in-house production of CAR-T cells is highly efficient and fast. Clinical response rate is high. CAR-T cells can be successfully produced for 99% of patients in just 9 to 10 days. Cells derived from ALL patients demonstrate a higher proliferation rate and contain higher frequencies of CAR-T cells and naïve T cells than of NHL patients. In addition, understanding the differences between CAR-T and TIL infusion products, may provide an angle to develop CAR-T cells for the treatment of solid tumors in the future.

Trial registration number

ClinicalTrials.gov; CAR-T: NCT02772198, First posted: May 13, 2016; TIL: NCT00287131, First posted: February 6, 2006.

Large-scale in vitro production of red blood cells from human peripheral blood mononuclear cells

Transfusion of donor-derived red blood cells (RBC) is the most common form of cellular therapy. Donor availability and the potential risk of alloimmunization and other transfusion-related complications may, however, limit the availability of transfusion units, especially for chronically transfused patients. In vitro cultured, customizable RBC would negate these concerns and further increase precision medicine. Large-scale, cost-effective production depends on optimization of culture conditions. We developed a defined medium and adapted our protocols to good manufacturing practice (GMP) culture requirements, which reproducibly provided pure erythroid cultures from peripheral blood mononuclear cells without prior CD34+ isolation, and a 3 × 107-fold increase in erythroblasts in 25 days (or from 100 million peripheral blood mononuclear cells, 2 to 4 mL packed red cells can be produced). Expanded erythroblast cultures could be differentiated to CD71dimCD235a+CD44+CD117-DRAQ5- RBC in 12 days. More than 90% of the cells enucleated and expressed adult hemoglobin as well as the correct blood group antigens. Deformability and oxygen-binding capacity of cultured RBC was comparable to in vivo reticulocytes. Daily RNA sampling during differentiation followed by RNA-sequencing provided a high-resolution map/resource of changes occurring during terminal erythropoiesis. The culture process was compatible with upscaling using a G-Rex bioreactor with a capacity of 1 L per reactor, allowing transition toward clinical studies and small-scale applications.

Streamlined production of genetically modified T cells with activation, transduction and expansion in closed-system G-Rex bioreactors

BACKGROUND

Gas Permeable Rapid Expansion (G-Rex) bioreactors have been shown to efficiently expand immune cells intended for therapeutic use, but do not address the complexity of the viral transduction step required for many engineered T-cell products. Here we demonstrate a novel method for transduction of activated T cells with Vectofusin-1 reagent. Transduction is accomplished in suspension, in G-Rex bioreactors. The simplified transduction step is integrated into a streamlined process that uses a single bioreactor with limited operator intervention.

METHODS

Peripheral blood mononuclear cells (PBMCs) from healthy donors were thawed, washed and activated with soluble anti-CD3 and anti-CD28 antibodies either in cell culture bags or in G-Rex bioreactors. Cells were cultured in TexMACS GMP medium with interleukin (IL)-7 and IL-15 and transduced with RetroNectin in bags or Vectorfusin-1 in the G-Rex. Total viable cell number, fold expansion, viability, transduction efficiency, phenotype and function were compared between the two processes.

RESULTS

The simplified process uses a single vessel from activation through harvest and achieves 56% transduction with 29-fold expansion in 11 days. The cells generated in the simplified process do not differ from cells produced in the conventional bag-based process functionally or phenotypically.

DISCUSSION

This study demonstrates that T cells can be transduced in suspension. Further, the conventional method of generating engineered T cells in bags for clinical use can be streamlined to a much simpler, less-expensive process without compromising the quality or function of the cell product.

Transposon-Based CAR T Cells in Acute Leukemias: Where are We Going?

Chimeric Antigen Receptor (CAR) T-cell therapy has become a new therapeutic reality for refractory and relapsed leukemia patients and is also emerging as a potential therapeutic option in solid tumors. Viral vector-based CAR T-cells initially drove these successful efforts; however, high costs and cumbersome manufacturing processes have limited the widespread clinical implementation of CAR T-cell therapy. Here we will discuss the state of the art of the transposon-based gene transfer and its application in CAR T immunotherapy, specifically focusing on the Sleeping Beauty (SB) transposon system, as a valid cost-effective and safe option as compared to the viral vector-based systems. A general overview of SB transposon system applications will be provided, with an update of major developments, current clinical trials achievements and future perspectives exploiting SB for CAR T-cell engineering. After the first clinical successes achieved in the context of B-cell neoplasms, we are now facing a new era and it is paramount to advance gene transfer technology to fully exploit the potential of CAR T-cells towards next-generation immunotherapy.

Rapid Transduction and Expansion of Transduced T Cells with Maintenance of Central Memory Populations

Chimeric antigen receptor (CAR)-T cells show great promise in treating cancers and viral infections. However, most protocols developed to expand T cells require relatively long periods of time in culture, potentially leading to progression toward populations of terminally differentiated effector memory cells. Here, we describe in detail a 9-day protocol for CAR gene transduction and expansion of primary rhesus macaque peripheral blood mononuclear cells (PBMCs). Cells produced and expanded with this method show high levels of viability, high levels of co-expression of two transduced genes, retention of the central memory phenotype, and sufficient quantity for immunotherapeutic infusion of 1-2 × 108 cells/kg in a 10 kg rhesus macaque. This 9-day protocol may be broadly used for CAR-T cell and other T cell immunotherapy approaches to decrease culture time and increase maintenance of central memory populations.

Platforms for Clinical-Grade CAR-T Cell Expansion

Chimeric antigen receptor (CAR)-T cell therapy has revolutionized the immunotherapy field with high rate complete responses especially for hematological diseases. Despite the diversity of tumor specific-antigens, the manufacturing process is consistent and involves multiple steps, including selection of T cells, activation, genetic modification, and in vitro expansion. Among these complex manufacturing phases, the choice of culture system to generate a high number of functional cells needs to be evaluated and optimized. Flasks, bags, and rocking motion bioreactor are the most used platforms for CAR-T cell expansion in the current clinical trials but are far from being standardized. New processing options are available and a systematic effort seeking automation, standardization and the increase of production scale, would certainly help to bring the costs down and ultimately democratize this personalized therapy. In this review, we describe different cell expansion platforms available as well as the quality control requirements for clinical-grade production.

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

The G-Rex cell culture platform is based on a gas-permeable membrane technology that provides numerous advantages over other systems. Conventional bioreactor platform technologies developed for large scale mammalian cell expansion are typically constrained by the mechanics of delivering oxygen to an expanding cell population. These systems often utilize complex mechanisms to enhance oxygen delivery, such as stirring, rocking, or perfusion, which adds to expense and increases their overall risk of failure. On the other hand, G-Rex gas-permeable membrane-based bioreactors provide a more physiologic environment and avoid the risk and cost associated with more complex systems. The result is a more robust, interacting cell population established through unlimited oxygen and nutrients that are available on demand. By removing the need to actively deliver oxygen, these bioreactors can hold larger medium volumes (more nutrients) which allows the cells to reach a maximum density without complexity or need for media exchange. This platform approach is scaled to meet the needs of research through commercial production with a direct, linear correlation between small and large devices. In the G-Rex platform, examples of cell expansion (9-14 day duration) include; CAR-T cells, which have atypical harvest density of 20-30 × 10⁶/cm² (or 2-3 × 10⁹ cells in a 100 cm² device); NK cells, which have a typical harvest density of 20-30 × 10⁶/cm² (or 2-3 × 10⁹ cells in a 100 cm² device) and numerous other cell types that proliferate without the need for intervention or complex processes normally associated with large scale culture. Here we describe the methods and concepts used to optimize expansion of various cell types in the static G-Rex bioreactor platform.

Engineering antigen-specific NK cell lines against the melanoma-associated antigen tyrosinase via TCR gene transfer

Introduction of Chimeric Antigen Receptors to NK cells has so far been the main practical method for targeting NK cells to specific surface antigens. In contrast, T cell receptor (TCR) gene delivery can supply large populations of cytotoxic T-lymphocytes (CTL) targeted against intracellular antigens. However, a major barrier in the development of safe CTL-TCR therapies exists, wherein the mispairing of endogenous and genetically transferred TCR subunits leads to formation of TCRs with off-target specificity. To overcome this and enable specific intracellular antigen targeting, we have tested the use of NK cells for TCR gene transfer to human cells. Our results show that ectopic expression of TCR α/β chains, along with CD3 subunits, enables the functional expression of an antigen-specific TCR complex on NK cell lines NK-92 and YTS, demonstrated by using a TCR against the HLA-A2-restricted tyrosinase-derived melanoma epitope, Tyr_368-377 . Most importantly, the introduction of a TCR complex to NK cell lines enables MHC-restricted, antigen-specific killing of tumor cells both in vitro and in vivo. Targeting of NK cells via TCR gene delivery stands out as a novel tool in the field of adoptive immunotherapy which can also overcome the major hurdle of "mispairing" in TCR gene therapy.

Novel biomanufacturing platform for large-scale and high-quality human T cells production

The adoptive transfer of human T cells or genetically-engineered T cells with cancer-targeting receptors has shown tremendous promise for eradicating tumors in clinical trials. The objective of this study was to develop a novel T cell biomanufacturing platform using stirred-tank bioreactor for large-scale and high-quality cellular production. First, various factors, such as bioreactor parameters, media, supplements, stimulation, seed age, and donors, were investigated. A serum-free fed-batch bioproduction process was developed to achieve 1000-fold expansion within 8 days after first stimulation and another 500-fold expansion with second stimulation. Second, this biomanufacturing process was successfully scaled up in bioreactor with dilution factor of 10, and the robustness and reproducibility of the process was confirmed by the inclusion of different donors' T cells of various qualities. Finally, T cell quality was monitored using 12 surface markers and 3 intracellular cytokines as the critical quality assessment criteria in early, middle and late stages of cell production. In this study, a new biomanufacturing platform was created to produce reliable, reproducible, high-quality, and large-quantity (i.e. > 5 billion) human T cells in stirred-tank bioreactor. This platform is compatible with the production systems of monoclonal antibodies, vaccines, and other therapeutic cells, which provides not only the proof-of-concept but also the ready-to-use new approach of T cell expansion for clinical immune therapy.

Enabling Large-Scale Ex Vivo Production of Megakaryocytes from CD34+ Cells Using Gas-Permeable Surfaces

Patients suffering from acute or sustained thrombocytopenia require platelet transfusions, which are entirely donor-based and limited by challenges related to storage and fluctuating supply. Developing cell-culture technologies will enable ex vivo and donor-independent platelet production. However, critical advancements are needed to improve scalability and increase megakaryocyte (Mk) culture productivity. To address these needs, we evaluated Mk production from mobilized peripheral blood CD34⁺ cells cultured on a commercially available gas-permeable silicone rubber membrane, which provides efficient gas exchange, and investigated the use of fed-batch media dilution schemes. Starting with a cell-surface density of 40 × 10³ CD34⁺ cells per cm² (G40D), culturing cells on the membrane for the first 5 days and employing media dilutions yielded 39 ± 19 CD41⁺ CD42b⁺ Mks per input CD34⁺ cell by day 11-a 2.2-fold increase compared with using standard culture surfaces and full media exchanges. By day 7, G40D conditions generated 1.5-fold more CD34⁺ cells and nearly doubled the numbers of Mk progenitors. The increased number of Mk progenitors coupled with media dilutions, potentially due to the retention of interleukin (IL)-3, increased Mk production in G40D. Compared with controls, G40D had higher viability, yielded threefold more Mks per milliliter of media used and exhibited lower mean ploidy, but had higher numbers of high-ploidy Mks. Finally, G40D-Mks produced proplatelets and platelet-like-particles that activate and aggregate upon stimulation. These results highlight distinct improvements in Mk cell-culture and demonstrate how new technologies and techniques are needed to enable clinically relevant production of Mks for platelet generation and cell-based therapies.

Manufacturing chimeric antigen receptor T cells: issues and challenges

Clinical trials of adoptively transferred CD19 chimeric antigen receptor (CAR) T cells have delivered unprecedented responses in patients with relapsed refractory B-cell malignancy. These results have prompted Food and Drug Administration (FDA) approval of two CAR T-cell products in this high-risk patient population. The widening range of indications for CAR T-cell therapy and increasing patient numbers present a significant logistical challenge to manufacturers aiming for reproducible delivery systems for high-quality clinical CAR T-cell products. This review discusses current and novel CAR T-cell processing methodologies and the quality control systems needed to meet the increasing clinical demand for these exciting new therapies.

Scaling up the Manufacturing Process of Adoptive T Cell Immunotherapy

Adoptive T cell immunotherapy, involving the reprogramming of immune cells to target specific cancer or virus-infected cells, has been recognized as a promising novel approach for the treatment of complex diseases. The impressive global momentum of this therapeutic approach has highlighted the urgent need for establishing it as an effective and standardized onco-therapeutic approach in a large manufacturing scale. However, given its heterogeneity and uncertainty in nature, adoptive T cell immunotherapy is associated with a high failure rate that restricts its manufacturing to a limited number of institutions worldwide. It is undoubted that quite a few major challenges must be met before engineered T cells can be considered as a reliable, safe, and effective remedy for a broad range of diseases with global-wise patient benefits. Here, the fundamental challenges that as yet remain unsolved in the manufacturing process before adoptive T cell therapy can be considered as a key element in the next generation of precision medicine is reviewed. It is proposed that it is necessary to adopt a closed system, automation, cost-effective manufacturing model, and quality-by-design (QbD) strategy to enable scaled up manufacturing of adoptive T cell immunotherapy; and it is challenging to choose appropriate bioreactors, parameters, and infrastructure in this process.

Expansion of Tumor-Infiltrating Lymphocytes from Melanoma Tumors

Autologous, in vitro-expanded tumor-infiltrating lymphocytes (TIL) have been successfully used for treatment of melanoma patients. Expansion of TIL from tumors is usually performed in two steps. The details of the procedure differ between different laboratories, but the general concept remains the same. In the first step, small fragments of a tumor are placed in culture medium containing one or more T cell stimulating growth factors. Here the most common protocol using interleukin (IL)-2 is described. The length of the first step is flexible to allow generation of enough cell to start the second step of the procedure. The second step is a so-called rapid expansion protocol (REP) where harvested TIL from the first step are induced to massive proliferation via triggering of their T cell receptor (TCR) complex in presence of an excess of feeder cells and, again, T cell stimulating growth factors. This second expansion step is usually around 2 weeks in length. Here will be described a REP that uses soluble anti-CD3 antibodies for TCR triggering, irradiated peripheral blood mononuclear cells (PBMC) as feeder cells, and IL-2 as the T cell growth factor. Furthermore, the described protocol utilizes gas-permeable cell culture flasks that yield large number of cells similar to conventional bioreactors but using standard laboratory equipment.

Tumor-infiltrating lymphocytes: Streamlining a complex manufacturing process

Adoptive cell therapy of tumor-infiltrating lymphocytes has shown promise for treatment of refractory melanoma and other solid malignancies; however, challenges to manufacturing have limited its widespread use. Traditional manufacturing efforts were lengthy, cumbersome and used open culture systems. We describe changes in testing and manufacturing that decreased the process cycle time, enhanced the robustness of critical quality attribute testing and facilitated a functionally closed system. These changes have enabled export of the manufacturing process to support multi-center clinical trials.

Restoring antiviral immunity with adoptive transfer of ex-vivo generated T cells

PURPOSE OF REVIEW

Latent viruses such as cytomegalovirus (CMV), Epstein-Barr virus (EBV) and adenovirus (ADV) often reactivate in immunocompromised patients, contributing to poor clinical outcomes. A rapid reconstitution of antiviral responses via adoptive transfer of virus-specific T cells (VSTs) can prevent or eradicate even refractory infections. Here, we evaluate this strategy and the associated methodological, manufacturing and clinical advances.

RECENT FINDINGS

From the early pioneering but cumbersome efforts to isolate CMV-specific T cell clones, new approaches and techniques have been developed to provide quicker, safer and broader-aimed ex-vivo antigen-specific cells. New manufacturing strategies, such as the use of G-Rex flasks or 'priming' with a library of overlapping viral peptides, allow for culturing greater numbers of cells that could be patient-specific or stored in cell banks for off-the-shelf applications. Rapid isolation of T cells using major histocompatibility complex tetramer or cytokine capture approaches, or genetic reprogramming of cells to target viral antigens can accelerate the generation of potent cellular products.

SUMMARY

Advances in the ex-vivo generation of VSTs in academic medical centres and as off-the-shelf blood bank-based or commercially produced reagents are likely to result in broader accessibility and possible manufacturing cost reduction of these cell products, and will open new therapeutic prospects for vulnerable and critically ill immunocompromised patients.

Automated Expansion of Primary Human T Cells in Scalable and Cell-Friendly Hydrogel Microtubes for Adoptive Immunotherapy

Adoptive immunotherapy is a highly effective strategy for treating many human cancers, such as melanoma, cervical cancer, lymphoma, and leukemia. Here, a novel cell culture technology is reported for expanding primary human T cells for adoptive immunotherapy. T cells are suspended and cultured in microscale alginate hydrogel tubes (AlgTubes) that are suspended in the cell culture medium in a culture vessel. The hydrogel tubes protect cells from hydrodynamic stresses and confine the cell mass less than 400 µm (in radial diameter) to ensure efficient mass transport, creating a cell-friendly microenvironment for growing T cells. This system is simple, scalable, highly efficient, defined, cost-effective, and compatible with current good manufacturing practices. Under optimized culture conditions, the AlgTubes enable culturing T cells with high cell viability, low DNA damage, high growth rate (≈320-fold expansion over 14 days), high purity (≈98% CD3+), and high yield (≈3.2 × 10⁸ cells mL^-1 hydrogel). All offer considerable advantages compared to current T cell culturing approaches. This new culture technology can significantly reduce the culture volume, time, and cost, while increasing the production.

Manufacturing development and clinical production of NKG2D chimeric antigen receptor-expressing T cells for autologous adoptive cell therapy

BACKGROUND AIMS

Adoptive cell therapy employing natural killer group 2D (NKG2D) chimeric antigen receptor (CAR)-modified T cells has demonstrated preclinical efficacy in several model systems, including hematological and solid tumors. We present comprehensive data on manufacturing development and clinical production of autologous NKG2D CAR T cells for treatment of acute myeloid leukemia and multiple myeloma (ClinicalTrials.gov Identifier: NCT02203825). An NKG2D CAR was generated by fusing native full-length human NKG2D to the human CD3ζ cytoplasmic signaling domain. NKG2D naturally associates with native costimulatory molecule DAP10, effectively generating a second-generation CAR against multiple ligands upregulated during malignant transformation including MIC-A, MIC-B and the UL-16 binding proteins.

METHODS

CAR T cells were infused fresh after a 9-day process wherein OKT3-activated T cells were genetically modified with replication-defective gamma-retroviral vector and expanded ex vivo for 5 days with recombinant human interleukin-2.

RESULTS

Despite sizable interpatient variation in originally collected cells, release criteria, including T-cell expansion and purity (median 98%), T-cell transduction (median 66% CD8⁺ T cells), and functional activity against NKG2D ligand-positive cells, were met for 100% of healthy donors and patients enrolled and collected. There was minimal carryover of non-T cells, particularly malignant cells; both effector memory and central memory cells were generated, and inflammatory cytokines such as granulocyte colony-stimulating factor, RANTES, interferon-γ and tumor necrosis factor-α were selectively up-regulated.

CONCLUSIONS

The process resulted in production of required cell doses for the first-in-human phase I NKG2D CAR T clinical trial and provides a robust, flexible base for further optimization of NKG2D CAR T-cell manufacturing.

Industrializing Autologous Adoptive Immunotherapies: Manufacturing Advances and Challenges

Cell therapy has proven to be a burgeoning field of investigation, evidenced by hundreds of clinical trials being conducted worldwide across a variety of cell types and indications. Many cell therapies have been shown to be efficacious in humans, such as modified T-cells and natural killer (NK) cells. Adoptive immunotherapy has shown the most promise in recent years, with particular emphasis on autologous cell sources. Chimeric Antigen Receptor (CAR)-based T-cell therapy targeting CD19-expressing B-cell leukemias has shown remarkable efficacy and reproducibility in numerous clinical trials. Recent marketing approval of Novartis' Kymriah™ (tisagenlecleucel) and Gilead/Kite's Yescarta™ (axicabtagene ciloleucel) by the FDA further underscores both the promise and legwork to be done if manufacturing processes are to become widely accessible. Further work is needed to standardize, automate, close, and scale production to bring down costs and democratize these and other cell therapies. Given the multiple processing steps involved, commercial-scale manufacturing of these therapies necessitates tighter control over process parameters. This focused review highlights some of the most recent advances used in the manufacturing of therapeutic immune cells, with a focus on T-cells. We summarize key unit operations and pain points around current manufacturing solutions. We also review emerging technologies, approaches and reagents used in cell isolation, activation, transduction, expansion, in-process analytics, harvest, cryopreservation and thaw, and conclude with a forward-look at future directions in the manufacture of adoptive immunotherapies.

CAR T cell therapy for breast cancer: harnessing the tumor milieu to drive T cell activation

BACKGROUND

The adoptive transfer of T cells redirected to tumor via chimeric antigen receptors (CARs) has produced clinical benefits for the treatment of hematologic diseases. To extend this approach to breast cancer, we generated CAR T cells directed against mucin1 (MUC1), an aberrantly glycosylated neoantigen that is overexpressed by malignant cells and whose expression has been correlated with poor prognosis. Furthermore, to protect our tumor-targeted cells from the elevated levels of immune-inhibitory cytokines present in the tumor milieu, we co-expressed an inverted cytokine receptor linking the IL4 receptor exodomain with the IL7 receptor endodomain (4/7ICR) in order to transform the suppressive IL4 signal into one that would enhance the anti-tumor effects of our CAR T cells at the tumor site.

METHODS

First (1G - CD3ζ) and second generation (2G - 41BB.CD3ζ) MUC1-specific CARs were constructed using the HMFG2 scFv. Following retroviral transduction transgenic expression of the CAR±ICR was assessed by flow cytometry. In vitro CAR/ICR T cell function was measured by assessing cell proliferation and short- and long-term cytotoxic activity using MUC1+ MDA MB 468 cells as targets. In vivo anti-tumor activity was assessed using IL4-producing MDA MB 468 tumor-bearing mice using calipers to assess tumor volume and bioluminescence imaging to track T cells.

RESULTS

In the IL4-rich tumor milieu, 1G CAR.MUC1 T cells failed to expand or kill MUC1+ tumors and while co-expression of the 4/7ICR promoted T cell expansion, in the absence of co-stimulatory signals the outgrowing cells exhibited an exhausted phenotype characterized by PD-1 and TIM3 upregulation and failed to control tumor growth. However, by co-expressing 2G CAR.MUC1 (signal 1 - activation + signal 2 - co-stimulation) and 4/7ICR (signal 3 - cytokine), transgenic T cells selectively expanded at the tumor site and produced potent and durable tumor control in vitro and in vivo.

CONCLUSIONS

Our findings demonstrate the feasibility of targeting breast cancer using transgenic T cells equipped to thrive in the suppressive tumor milieu and highlight the importance of providing transgenic T cells with signals that recapitulate physiologic TCR signaling - [activation (signal 1), co-stimulation (signal 2) and cytokine support (signal 3)] - to promote in vivo persistence and memory formation.

CAR T Cells in Trials: Recent Achievements and Challenges that Remain in the Production of Modified T Cells for Clinical Applications

The adoptive transfer of chimeric antigen receptor (CAR)-modified T cells is attracting growing interest for the treatment of malignant diseases. Early trials with anti-CD19 CAR T cells have achieved spectacular remissions in B-cell leukemia and lymphoma, so far refractory, very recently resulting in the Food and Drug Administration approval of CD19 CAR T cells for therapy. With further applications and increasing numbers of patients, the reproducible manufacture of high-quality clinical-grade CAR T cells is becoming an ever greater challenge. New processing techniques, quality-control mechanisms, and logistic developments are required to meet both medical needs and regulatory restrictions. This paper summarizes the state-of-the-art in manufacturing CAR T cells and the current challenges that need to be overcome to implement this type of cell therapy in the treatment of a variety of malignant diseases and in a greater number of patients.