CAR-T Cell Therapies From the Transfusion Medicine Perspective

CAR-T cell manufacturing landscape-Lessons from the past decade and considerations for early clinical development

CAR-T cell therapies have consolidated their position over the last decade as an effective alternative to conventional chemotherapies for the treatment of a number of hematological malignancies. With an exponential increase in the number of commercial therapies and hundreds of phase 1 trials exploring CAR-T cell efficacy in different settings (including autoimmunity and solid tumors), demand for manufacturing capabilities in recent years has considerably increased. In this review, we explore the current landscape of CAR-T cell manufacturing and discuss some of the challenges limiting production capacity worldwide. We describe the latest technical developments in GMP production platform design to facilitate the delivery of a range of increasingly complex CAR-T cell products, and the challenges associated with translation of new scientific developments into clinical products for patients. We explore all aspects of the manufacturing process, namely early development, manufacturing technology, quality control, and the requirements for industrial scaling. Finally, we discuss the challenges faced as a small academic team, responsible for the delivery of a high number of innovative products to patients. We describe our experience in the setup of an effective bench-to-clinic pipeline, with a streamlined workflow, for implementation of a diverse portfolio of phase 1 trials.

Granulocyte Colony Stimulating Factor-Mobilized Peripheral Blood Mononuclear Cells: An Alternative Cellular Source for Chimeric Antigen Receptor Therapy

Lymphocyte collection by apheresis for CAR-T production usually does not include blood mobilized using granulocyte colony stimulating factor (G-CSF) due to the widespread knowledge that it causes a decrease in the number and functionality of lymphocytes. However, it is used for stem cell transplant, which is a common treatment for hematological malignancies. The growing demand for CAR therapies (CAR-T and NK-CAR), both in research and clinics, makes it necessary to evaluate whether mobilized PBSC products may be potential candidates for use in such therapies. This review collects recent works that experimentally verify the role and functionality of T and NK lymphocytes and the generation of CAR-T from apheresis after G-CSF mobilization. As discussed, T cells do not vary significantly in their phenotype, the ratio of CD4+ and CD8+ remains constant, and the different sub-populations remain stable. In addition, the expansion and proliferation rates are invariant regardless of mobilization with G-CSF as well as the secretion of proinflammatory cytokines and the cytotoxic ability. Therefore, cells mobilized before apheresis are postulated as a new alternative source of T cells for adoptive therapies that will serve to alleviate high demand, increase availability, and take advantage of the substantial number of existing cryopreserved products.

Update on the current and future use of CAR-T to treat multiple myeloma

Chimeric antigen receptor T-cell (CAR-T) therapy has become an important intervention in the management of relapsed and relapsed/refractory multiple myeloma (MM). Currently, B-cell maturation antigen (BCMA) is the most targeted surface protein due to its ubiquitous expression on plasma cells, with increasing expression of this essential transmembrane protein on malignant plasma cells as patients develop more advanced disease. This review will explore the earliest CAR-T trials in myeloma, discuss important issues involved in CAR-T manufacturing and processing, as well as review current clinical trials that led to the approval of the two commercially available CAR-T products, Idecabtagene vicleucel and ciltacabtagene autoleucel. The most recent data from trials investigating the use of CAR-T as an earlier line of therapy will be presented. Finally, the problem of relapses after CAR-T will be presented, including several theories as to why CAR-T therapies fail and possible clinical caveats. The next generation of MM-specific CAR-T will likely include new targets such as G-protein-coupled receptor class C, Group 5, member D (GPRC5D) and signaling lymphocyte activation molecular Family 7 (SLAMF7). The role of CAR-T in the treatment of MM will undoubtedly increase exponentially in the next decade.

Particle-Based Artificial Antigen-Presenting Cell Systems for T Cell Activation in Adoptive T Cell Therapy

T cell-based adoptive cell therapy (ACT) has emerged as a promising treatment for various diseases, particularly cancers. Unlike other immunotherapy modalities, ACT involves directly transferring engineered T cells into patients to eradicate diseased cells; hence, it necessitates methods for effectively activating and expanding T cells in vitro. Artificial antigen-presenting cells (aAPCs) have been widely developed based on biomaterials, particularly micro- and nanoparticles, and functionalized with T cell stimulatory antibodies to closely mimic the natural T cell-APC interactions. Due to their vast clinical utility, aAPCs have been employed as an off-the-shelf technology for T cell activation in FDA-approved ACTs, and the development of aAPCs is constantly advancing with the emergence of aAPCs with more sophisticated designs and additional functionalities. Here, we review the recent advancements in particle-based aAPCs for T cell activation in ACTs. Following a brief introduction, we first describe the manufacturing processes of ACT products. Next, the design and synthetic strategies for micro- and nanoparticle-based aAPCs are discussed separately to emphasize their features, advantages, and limitations. Then, the impact of design parameters of aAPCs, such as size, shape, ligand density/mobility, and stiffness, on their functionality and biomedical performance is explored to provide deeper insights into the design concepts and principles for more efficient and safer aAPCs. The review concludes by discussing current challenges and proposing future perspectives for the development of more advanced aAPCs.

Boosting immune responses in lung tumor immune microenvironment: A comprehensive review of strategies and adjuvants

The immune system has a substantial impact on the growth and expansion of lung malignancies. Immune cells are encompassed by a stroma comprising an extracellular matrix (ECM) and different cells like stromal cells, which are known as the tumor immune microenvironment (TIME). TME is marked by the presence of immunosuppressive factors, which inhibit the function of immune cells and expand tumor growth. In recent years, numerous strategies and adjuvants have been developed to extend immune responses in the TIME, to improve the efficacy of immunotherapy. In this comprehensive review, we outline the present knowledge of immune evasion mechanisms in lung TIME, explain the biology of immune cells and diverse effectors on these components, and discuss various approaches for overcoming suppressive barriers. We highlight the potential of novel adjuvants, including toll-like receptor (TLR) agonists, cytokines, phytochemicals, nanocarriers, and oncolytic viruses, for enhancing immune responses in the TME. Ultimately, we provide a summary of ongoing clinical trials investigating these strategies and adjuvants in lung cancer patients. This review also provides a broad overview of the current state-of-the-art in boosting immune responses in the TIME and highlights the potential of these approaches for improving outcomes in lung cancer patients.

Leukapheresis for CAR-T cell production and therapy

Chimeric antigen receptor (CAR) T-cell therapy is an effective, individualized immunotherapy, and novel treatment for hematologic malignancies. Six commercial CAR-T cell products are currently approved for lymphatic malignancies and multiple myeloma. In addition, an increasing number of clinical centres produce CAR-T cells on-site, which enable the administration of CAR-T cells on site. The CAR-T cell products are either fresh or cryopreserved. Manufacturing CAR-T cells is a complicated process that begins with leukapheresis to obtain T cells from the patient's peripheral blood. An optimal leukapheresis product is crucial step for a successful CAR-T cell therapy; therefore, it is imperative to understand the factors that may affect the quality or T cells. The leukapheresis for CAR-T cell production is well tolerated and safe for both paediatric and adult patients and CAR-Τ cell therapy presents high clinical response rate in many studies. CAR-T cell therapy is under continuous improvement, and it has transformed into an almost standard procedure in clinical haematology and stem cell transplantation facilities that provide both autologous and allogeneic stem cell transplantations. In patients suffering from advanced haematological malignancies, CAR-T cell therapy shows incredible antitumor efficacy. Even after a single infusion of autologous CD19-targeting CAR-T cells in patients with relapsed or refractory diffuse large B cell lymphoma (DLBCL) and acute lymphoblastic leukaemia (ALL), long lasting remission is observed, and a fraction of the patients are being cured. Future novel constructs are being developed with better T cell persistence and better expansion. New next-generation CAR-T cells are currently designed to avoid toxicities such as cytokine release syndrome and neurotoxicity.

Managing leukapheresis in adult and pediatric patients eligible for chimeric antigen receptor T-cell therapy: suggestions from an Italian Expert Panel

Chimeric antigen receptor (CAR) T-cell therapy relies on T cells engineered to target specific tumor antigens such as CD-19 in B-cell malignancies. In this setting, the commercially available products have offered a potential long-term cure for both pediatric and adult patients. Yet manufacturing CAR T cells is a cumbersome, multistep process, the success of which strictly depends on the characteristics of the starting material, i.e., lymphocyte collection yield and composition. These, in turn, might be affected by patient factors such as age, performance status, comorbidities, and previous therapies. Ideally, CAR T-cell therapies are a one-off treatment; therefore, optimization and the possible standardization of the leukapheresis procedure is critical, also in view of the novel CAR T cells currently under investigation for hematological malignancies and solid tumors. The most recent Best Practice recommendations for the management of children and adults undergoing CAR T-cell therapy provide a comprehensive guide to their use. However, their application in local practice is not straightforward and some grey areas remain. An Italian Expert Panel of apheresis specialists and hematologists from the centers authorized to administer CAR T-cell therapy took part in a detailed discussion on the following: 1) pre-apheresis patient evaluation; 2) management of the leukapheresis procedure, also in special situations represented by low lymphocyte count, peripheral blastosis, pediatric population <25 kg, and the COVID-19 outbreak; and 3) release and cryopreservation of the apheresis unit. This article presents some of the important challenges that must be faced to optimize the leukapheresis procedure and offers suggestions as to how to improve it, some of which are specific to the Italian setting.

Promises and challenges of a decentralized CAR T-cell manufacturing model

Autologous chimeric antigen receptor-modified T-cell (CAR T) products have demonstrated un-precedent efficacy in treating many relapsed/refractory B-cell and plasma cell malignancies, leading to multiple commercial products now in routine clinical use. These positive responses to CAR T therapy have spurred biotech and big pharma companies to evaluate innovative production methods to increase patient access while maintaining adequate quality control and profitability. Autologous cellular therapies are, by definition, manufactured as single patient batches, and demand has soared for manufacturing facilities compliant with current Good Manufacturing Practice (cGMP) regulations. The use of a centralized production model is straining finite resources even in developed countries in North America and the European Union, and patient access is not feasible for most of the developing world. The idea of having a more uniform availability of these cell therapy products promoted the concept of point-of-care (POC) manufacturing or decentralized in-house production. While this strategy can potentially decrease the cost of manufacturing, the challenge comes in maintaining the same quality as currently available centrally manufactured products due to the lack of standardized manufacturing techniques amongst institutions. However, academic medical institutions and biotech companies alike have forged ahead innovating and adopting new technologies to launch clinical trials of CAR T products produced exclusively in-house. Here we discuss POC production of CAR T products.

Aptamer-Based Chromatographic Methods for Efficient and Economical Separation of Leukocyte Populations

The manufacturing process of chimeric antigen receptor T cell therapies includes isolation systems that provide pure T cells. Current magnetic-activated cell sorting and immunoaffinity chromatography methods produce desired cells with high purity and yield but require expensive equipment and reagents and involve time-consuming incubation steps. Here, we demonstrate that aptamers can be employed in a continuous-flow resin platform for both depletion of monocytes and selection of CD8+ T cells from peripheral blood mononuclear cells at low cost with high purity and throughput. Aptamer-mediated cell selection could potentially enable fully synthetic, traceless isolations of leukocyte subsets from a single isolation system.

A novel predictive algorithm to personalize autologous T-cell harvest for chimeric antigen receptor T-cell manufacture

BACKGROUND AIMS

The most widely accepted starting materials for chimeric antigen receptor T-cell manufacture are autologous CD3+ T cells obtained via the process of leukapheresis, also known as T-cell harvest. As this treatment modality gains momentum and apheresis units struggle to meet demand for harvest slots, strategies to streamline this critical step are warranted.

METHODS

This retrospective review of 262 T-cell harvests, with a control cohort of healthy donors, analyzed the parameters impacting CD3+ T-cell yield in adults with B-cell malignancies. The overall aim was to design a novel predictive algorithm to guide the required processed blood volume (PBV) (L) on the apheresis machine to achieve a specific CD3+ target yield.

RESULTS

Factors associated with CD3+ T-cell yield on multivariate analysis included peripheral blood CD3+ count (natural log, ×109/L), hematocrit (HCT) and PBV with coefficients of 0.86 (95% confidence interval [CI], 0.80-0.92, P < 0.001), 1.30 (95% CI, 0.51-2.08, P = 0.001) and 0.09 (95% CI, 0.07-0.11, P < 0.001), respectively. The authors' model, incorporating CD3+ cell count, HCT and PBV (L), with an adjusted R2 of 0.87 and root-mean-square error of 0.26 in the training dataset, was highly predictive of CD3+ cell yield in the testing dataset. An online application to estimate PBV using this algorithm can be accessed at https://cd3yield.shinyapps.io/cd3yield/.

CONCLUSIONS

The authors propose a transferrable model that incorporates clinical and laboratory variables accessible pre-harvest for use across the field of T-cell therapy. Pending further validation, such a model may be used to generate an individual leukapheresis plan and streamline the process of cell harvest, a well-recognized bottleneck in the industry.

T, NK, then macrophages: Recent advances and challenges in adaptive immunotherapy from human pluripotent stem cells

Adaptive cellular immunotherapy, especially chimeric antigen receptor-T (CAR-T) cell therapy, has advanced the treatment of hematological malignancy. However, major limitations still remain in the source of cells comes from the patients themselves. The use of human pluripotent stem cells to differentiate into immune cells, such as T cells, NK cells, and macrophages, then arm with chimeric antigen receptor (CAR) to enhance tumor killing has gained major attention. It is expected to solve the low number of immune cells recovery from patients, long waiting periods, and ethical issues(reprogramming somatic cells to produce induced pluripotent stem cells (iPS cells) avoids the ethical issues unique to embryonic stem cells (Lo and Parham, 2009). However, there are still major challenges to be further solved. This review summarizes the progress, challenges, and future direction in human pluripotent stem cell-based immunotherapy.

Evaluation of cell collection efficiency in non-mobilized adult donors for autologous chimeric antigen receptor T-cell manufacturing

BACKGROUND AND OBJECTIVES

Data about collection efficiency 1 (CE1), which takes into account blood cell counts before and after collection, thus providing a more accurate estimate, in the collection of autologous T lymphocytes by apheresis for chimeric antigen receptor (CAR) T-cells remain scarce. We evaluated donor- and procedure-related characteristics that might influence the CE1 of lymphocytes.

MATERIALS AND METHODS

We retrospectively reviewed all mononuclear cell (MNC) collections) performed for CAR T-cell manufacturing in our institution from May 2017 to June 2021 in adult patients. Age, gender, weight, total blood volume (TBV), prior haematopoietic cell transplant, diagnosis, days between last treatment and apheresis, pre-collection cell counts, duration of apheresis, TBV processed, vascular access, inlet flow and device type were analysed as potential factors affecting CE1 of lymphocytes.

RESULTS

A total of 127 autologous MNC collections were performed on 118 patients diagnosed with acute lymphoblastic leukaemia (n = 53, 45%), non-Hodgkin lymphoma (n = 40, 34%), multiple myeloma (n = 19, 16%), and chronic lymphocytic leukaemia (n = 6, 5%). The median CE1 of lymphocytes was 47% (interquartile range: 32%-65%). In multiple regression analysis, Amicus device was associated with higher CE1 of lymphocytes (p = 0.01) and lower CE1 of platelets (p < 0.01) when compared with Optia device.

CONCLUSION

The knowledge of the MNC and lymphocyte CE1 of each apheresis device used to collect cells for CAR T therapy, together with the goal of the number of cells required, is essential to define the volume to be processed and to ensure the success of the collection.

Cytokines as an important player in the context of CAR-T cell therapy for cancer: Their role in tumor immunomodulation, manufacture, and clinical implications

CAR-T cell therapies have been recognized as one of the most advanced and efficient strategies to treat patients with hematologic malignancies. However, similar results have not been observed for the treatment of solid tumors. One of the explanations is the fact that tumors have extremely hostile microenvironments for the infiltration and effector activity of T-cells, mainly due to the presence of highly suppressive cytokines, hypoxia, and reactive oxygen species. Taking advantage of cytokines functionally, new fourth-generation CAR constructs have been developed to target tumor cells and additionally release cytokines that can contribute to the cytotoxicity of T-cells. The manufacturing process, including the use of cytokines in the expansion and differentiation of T cells, is also discussed. Finally, the clinical aspects and the influence of cytokines on the clinical condition of patients, such as cytokine release syndrome, who receive treatment with CAR-T cells are addressed. Therefore, this review aims to highlight how important cytokines are as one of the major players of cell therapy.

Emerging Trends in Immunotherapy for Cancer

Recent advances in cancer immunology have enabled the discovery of promising immunotherapies for various malignancies that have shifted the cancer treatment paradigm. The innovative research and clinical advancements of immunotherapy approaches have prolonged the survival of patients with relapsed or refractory metastatic cancers. Since the U.S. FDA approved the first immune checkpoint inhibitor in 2011, the field of cancer immunotherapy has grown exponentially. Multiple therapeutic approaches or agents to manipulate different aspects of the immune system are currently in development. These include cancer vaccines, adoptive cell therapies (such as CAR-T or NK cell therapy), monoclonal antibodies, cytokine therapies, oncolytic viruses, and inhibitors targeting immune checkpoints that have demonstrated promising clinical efficacy. Multiple immunotherapeutic approaches have been approved for specific cancer treatments, while others are currently in preclinical and clinical trial stages. Given the success of immunotherapy, there has been a tremendous thrust to improve the clinical efficacy of various agents and strategies implemented so far. Here, we present a comprehensive overview of the development and clinical implementation of various immunotherapy approaches currently being used to treat cancer. We also highlight the latest developments, emerging trends, limitations, and future promises of cancer immunotherapy.

The EBMT Immune Effector Cell Nursing Guidelines on CAR-T Therapy: A Framework for Patient Care and Managing Common Toxicities

Chimeric antigen receptor T-cell (CAR T) therapy is a new and rapidly developing field. Centers across the world are gaining more experience using these innovative anti-cancer treatments, transitioning from the 'bench' to the 'bedside', giving benefit to an increasing number of patients. For those with some refractory hematological malignancies, CAR-T may offer a treatment option that was not available a few years ago. CAR-T therapy is an immune effector cell and precision/personalized medicine treatment which is tailored to the individual patient and associated with a variety of unique adverse events and toxicities that necessitate specialist nursing/medical vigilance in an appropriate clinical setting. Subtle unrecognized signs and symptoms can result in rapid deterioration and, possibly, life threatening cardiorespiratory and/or neurological sequelae. These guidelines have been prepared for nurses working in cellular therapy in inpatient, outpatient and ambulatory settings. Many nurses will encounter cellular therapy recipients indirectly, during the referral process, following discharge, and when patients are repatriated back to local centers. The aim of these guidelines is to provide all nurses with a practice framework to enable recognition, monitoring and grading of CAR-T therapy-associated toxicities, and to support and nurse these highly complex patients with confidence. They have been developed under the auspices of several bodies of the European society for Blood and Marrow Transplantation (EBMT), by experienced health professionals, and will be a valuable resource to all practitioners working in cellular therapy.

Stem-like memory T cells are generated during hollow fiber perfusion-based expansion and enriched after cryopreservation in an automated modular cell therapy manufacturing process

BACKGROUND AIMS

Modular automation is a flexible and reliable option to build the foundation of a new or evolving process or to introduce automation to a process that is already established. Herein the authors demonstrate that modular automation provides both high-quality and high-yield T-cell products.

METHODS

Cells from three individual donors collected on an automated continuous flow centrifugation system were successfully expanded in a functionally closed, automated, perfusion-based hollow fiber bioreactor. These cells were then prepared for cryopreservation in an automated closed-system device that maintains temperature and aliquots a mixed cell product and cryoprotectant into product bags. Cell product bags were thawed and expanded in flasks. Samples taken throughout this manufacturing process were analyzed for cell phenotype, exhaustion markers and functionality. The proportion of CD4+ and CD8+ T cells was maintained through each step, from pre-expansion and post-expansion to immediately after thaw and 24 h after thaw.

RESULTS

Interestingly, phenotypic markers such as CD45RO, CD45RA and CCR7 evolved throughout the process and stem-like memory T cells emerged as the predominant phenotype in the clinically relevant 24-h post-thaw sample.

CONCLUSIONS

Modular automation supported the generation of stem-like memory T cells that were not terminally exhausted and were able to produce effector cytokines upon restimulation.

EZH1 repression generates mature iPSC-derived CAR T cells with enhanced antitumor activity

Human induced pluripotent stem cells (iPSCs) provide a potentially unlimited resource for cell therapies, but the derivation of mature cell types remains challenging. The histone methyltransferase EZH1 is a negative regulator of lymphoid potential during embryonic hematopoiesis. Here, we demonstrate that EZH1 repression facilitates in vitro differentiation and maturation of T cells from iPSCs. Coupling a stroma-free T cell differentiation system with EZH1-knockdown-mediated epigenetic reprogramming, we generated iPSC-derived T cells, termed EZ-T cells, which display a highly diverse T cell receptor (TCR) repertoire and mature molecular signatures similar to those of TCRαβ T cells from peripheral blood. Upon activation, EZ-T cells give rise to effector and memory T cell subsets. When transduced with chimeric antigen receptors (CARs), EZ-T cells exhibit potent antitumor activities in vitro and in xenograft models. Epigenetic remodeling via EZH1 repression allows efficient production of developmentally mature T cells from iPSCs for applications in adoptive cell therapy.

State of the Art in the Current Management and Future Directions of Targeted Therapy for Differentiated Thyroid Cancer

Two-thirds of differentiated thyroid cancer (DTC) patients with distant metastases would be classified as radioactive iodine-refractory (RAIR-DTC), evolving into a poor outcome. Recent advances underlying DTC molecular mechanisms have shifted the therapy focus from the standard approach to targeting specific genetic dysregulations. Lenvatinib and sorafenib are first-line, multitargeted tyrosine kinase inhibitors (TKIs) approved to treat advanced, progressive RAIR-DTC. However, other anti-angiogenic drugs, including single targeted TKIs, are currently being evaluated as alternative or salvage therapy after the failure of first-line TKIs. Combinatorial therapy of mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K) signalling cascade inhibitors has become a highly advocated strategy to improve the low efficiency of the single agent treatment. Recent studies pointed out targetable alternative pathways to overcome the resistance to MAPK and PI3K pathways’ inhibitors. Because radioiodine resistance originates in DTC loss of differentiation, redifferentiation therapies are currently being explored for efficacy. The present review will summarize the conventional management of DTC, the first-line and alternative TKIs in RAIR-DTC, and the approaches that seek to overcome the resistance to MAPK and PI3K pathways’ inhibitors. We also aim to emphasize the latest achievements in the research of redifferentiation therapy, immunotherapy, and agents targeting gene rearrangements in advanced DTC.

Preparing for CAR T cell therapy: patient selection, bridging therapies and lymphodepletion

Chimeric antigen receptor (CAR) T cells have emerged as a potent therapeutic approach for patients with certain haematological cancers, with multiple CAR T cell products currently approved by the FDA for those with relapsed and/or refractory B cell malignancies. However, in order to derive the desired level of effectiveness, patients need to successfully receive the CAR T cell infusion in a timely fashion. This process entails apheresis of the patient's T cells, followed by CAR T cell manufacture. While awaiting infusion at an authorized treatment centre, patients may receive interim disease-directed therapy. Most patients will also receive a course of pre-CAR T cell lymphodepletion, which has emerged as an important factor in enabling durable responses. The time between apheresis and CAR T cell infusion is often not a simple journey, with each milestone being a critical step that can have important downstream consequences for the ability to receive the infusion and the strength of clinical responses. In this Review, we provide a summary of the many considerations for preparing patients with B cell non-Hodgkin lymphoma or acute lymphoblastic leukaemia for CAR T cell therapy, and outline current limitations and areas for future research.

Ex Vivo Model to Assess the Exposure of Patients to Plasticizers from Medical Devices during Pre-CAR-T Cells’ Apheresis

Background: The treatment of relapsed or refractory leukemia remains a major problem. Among the new therapeutic approaches, the use of modified T lymphocytes, called chimeric antigen receptor T cells (CAR-T cells), seems promising. The first step of their preparation is leukapheresis, which involves the collection of mononuclear cells from the patient. This medical procedure requires numerous medical devices (MDs) made of plasticized polyvinylchloride (PVC). These compounds can leach out of the devices during contact with the patient’s blood. The aim of our study was to evaluate the migration of the plasticizers contained in the MD during a simulated pre-CAR-T cell leukapheresis procedure, and to measure the patient’s and their lymphocytes’ exposure to them. Methods: The qualitative and quantitative composition of the MD used for pre-CAR-T cell apheresis was determined by gas chromatography–mass spectrometry (GC–MS). Then, an ex vivo leukapheresis model using an ethanol/water simulant was performed to evaluate the plasticizers’ migration under simulated clinical conditions of pre-CAR-T cells’ cytapheresis. The plasticizers released into the simulant were quantified by GC–MS. Results: Diethylhexylphthalate (DEHP) was found in the apheresis kit, with amounts ranging from 25% to 59% (g/100 g of PVC). Bis(2-ethylhexyl) adipate was detected at trace levels. A total of 98.90 ± 11.42 mg of DEHP was released into the simulant, corresponding to an exposure dose of 1.4 mg/kg for a 70 kg patient. Conclusions: Patients undergoing a pre-CAR-T cell apheresis are mainly exposed to DEHP, which can impact their health because of its endocrine disruption effect, but could also lead to a decrease in CAR-T cells’ efficiency/quality.

Quantitative and Functional Assessment of the Influence of Routinely Used Cryopreservation Media on Mononuclear Leukocytes for Medical Research

Quantitative and functional analysis of mononuclear leukocyte populations is an invaluable tool to understand the role of the immune system in the pathogenesis of a disease. Cryopreservation of mononuclear cells (MNCs) is routinely used to guarantee similar experimental conditions. Immune cells react differently to cryopreservation, and populations and functions of immune cells change during the process of freeze–thawing. To allow for a setup that preserves cell number and function optimally, we tested four different cryopreservation media. MNCs from 15 human individuals were analyzed. Before freezing and after thawing, the distribution of leukocytes was quantified by flow cytometry. Cultured cells were stimulated using lipopolysaccharide, and their immune response was quantified by flow cytometry, quantitative polymerase chain reaction (qPCR), and enzyme-linked immunosorbent assay (ELISA). Ultimately, the performance of the cryopreservation media was ranked. Cell recovery and viability were different between the media. Cryopreservation led to changes in the relative number of monocytes, T cells, B cells, and their subsets. The inflammatory response of MNCs was altered by cryopreservation, enhancing the basal production of inflammatory cytokines. Different cryopreservation media induce biases, which needs to be considered when designing a study relying on cryopreservation. Here, we provide an overview of four different cryopreservation media for choosing the optimal medium for a specific task.

The antigen-binding moiety in the driver's seat of CARs

Immuno-oncology has been at the forefront of cancer treatment in recent decades. In particular immune checkpoint and chimeric antigen receptor (CAR)-T cell therapy have achieved spectacular results. Over the years, CAR-T cell development has followed a steady evolutionary path, focusing on increasing T cell potency and sustainability, which has given rise to different CAR generations. However, there was less focus on the mode of interaction between the CAR-T cell and the cancer cell; more specifically on the targeting moiety used in the CAR and its specific properties. Recently, the importance of optimizing this domain has been recognized and the possibilities have been exploited. Over the last 10 years-in addition to the classical scFv-based CARs-single domain CARs, natural receptor-ligand CARs, universal CARs and CARs targeting more than one antigen have emerged. In addition, the specific parameters of the targeting domain and their influence on T cell activation are being examined. In this review, we concisely present the history of CAR-T cell therapy, and then expand on various developments in the CAR ectodomain. We discuss different formats, each with their own advantages and disadvantages, as well as the developments in affinity tuning, avidity effects, epitope location, and influence of the extracellular spacer.

Associação Brasileira de Hematologia, Hemoterapia e Terapia Celular Consensus on genetically modified cells. V: Manufacture and quality control

Chimeric antigen receptor T cells (CAR-T), especially against CD19 marker, present in lymphomas and acute B leukemia, enabled a revolution in the treatment of hematologic neoplastic diseases. The manufacture of CAR-T cells requires the adoption of GMP-compatible methods and it demands the collection of mononuclear cells from the patient (or from the donor), generally through the apheresis procedure, T cell selection, activation, transduction and expansion ex vivo, and finally storage, usually cryopreserved, until the moment of their use. An important aspect is the quality control testing of the final product, for example, the characterization of its identity and purity, tests to detect any contamination by microorganisms (bacteria, fungi, and mycoplasma) and its potency. The product thawing and intravenous infusion do not differ much from what is established for the hematopoietic progenitor cell product. After infusion, it is important to check for the presence and concentration of CAR-T cells in the patient's peripheral blood, as well as to monitor their clinical impact, for instance, the occurrence of short-term, such as cytokine release syndrome and neurological complications, and long-term complications, which require patient follow-up for many years.

Novel CS1 CAR-T Cells and Bispecific CS1-BCMA CAR-T Cells Effectively Target Multiple Myeloma

Multiple myeloma (MM) is a hematological cancer caused by abnormal proliferation of plasma cells in the bone marrow, and novel types of treatment are needed for this deadly disease. In this study, we aimed to develop novel CS1 CAR-T cells and bispecific CS1-BCMA CAR-T cells to specifically target multiple myeloma. We generated a new CS1 (CD319, SLAM-7) antibody, clone (7A8D5), which specifically recognized the CS1 antigen, and we applied it for the generation of CS1-CAR. CS1-CAR-T cells caused specific killing of CHO-CS1 target cells with secretion of IFN-gamma and targeted multiple myeloma cells. In addition, bispecific CS1-BCMA-41BB-CD3 CAR-T cells effectively killed CHO-CS1 and CHO-BCMA target cells, killed CS1/BCMA-positive multiple myeloma cells, and secreted IFN-gamma. Moreover, CS1-CAR-T cells and bispecific CS1-BCMA CAR-T cells effectively blocked MM1S multiple myeloma tumor growth in vivo. These data for the first time demonstrate that novel CS1 and bispecific CS1-BCMA-CAR-T cells are effective in targeting MM cells and provide a basis for future clinical trials.

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.

Platelet decrease and efficacy of platelet-rich plasma return following peripheral blood stem cell apheresis

BACKGROUND

Peripheral blood stem cell (PBSC) transplantation is a key treatment option for hematological diseases and is widely performed in clinical practice. Platelet loss is one of the major complications of PBSC apheresis, and platelet-rich plasma (PRP) return is considered in case of platelet decrease following apheresis; however, little is known about the frequency and severity of platelet loss and the efficacy of PRP return postapheresis.

METHODS

We assessed changes in platelet counts following PBSC-related apheresis in 270 allogeneic (allo)- and 105 autologous (auto)-PBSC settings. We also evaluated the efficacy of PRP transfusion on platelet recovery postapheresis.

RESULTS

In both allo- and auto-PBSC settings, the preapheresis platelet count (range, 84-385 and 33-558 × 10⁹ /L, respectively) decreased postapheresis (range, 57-292 and 20-429 × 10⁹ /L, respectively), whereas severe platelet decrease (<50 × 10⁹ /L) was only observed in auto-PBSC patients (n = 9). We confirmed that platelet count before apheresis was a risk factor for severe platelet decrease (<50 × 10⁹ /L) following auto-PBSC apheresis (odds ratio 0.749, P < .049). PRP return postapheresis facilitated platelet recovery in more than 80% of cases in both allo and auto settings.

CONCLUSION

Lower platelet count preapheresis is a useful predictor of severe platelet decrease following auto-PBSC apheresis and PRP return is an effective process to facilitate platelet recovery postapheresis.

TriBAFF-CAR-T cells eliminate B-cell malignancies with BAFFR-expression and CD19 antigen loss

Background

To investigate the effect of TriBAFF-CAR-T cells on hematological tumor cells.

Methods

TriBAFF-CAR-T and CD19-CAR-T cells were co-cultured with BAFFR-bearing B-cell malignancies at different effector/target ratios to evaluate the anti-tumor effects. In vivo, TriBAFF-CAR-T and CD19-CAR-T cells were intravenously injected into Raji-luciferase xenograft mice. CD19 antigens losing lymphoblasts was simulated by Raji knocking out CD19 (CD19^KO) to investigate the effect of TriBAFF-CAR-T cells on CD19^KO Raji.

Results

Both TriBAFF-CAR-T and CD19-CAR-T cells significantly induced the lysis of Raji, BALL-1, and Jeko-1. Moreover, when CD19-CAR-T cells specifically caused the lysis of K562 with overexpressed CD19, the lethal effect of TriBAFF-CAR-T cells was also specific for BAFFR-bearing K562 with increasing levels of interleukin-2 and INF-γ. The TriBAFF-CAR-T have the same effect with CD19-CAR-T cells in treating Raji xenofraft mice. TriBAFF-CAR-T cells also have great effect in CD19^KO Raji cells.

Conclusions

In this study, we successfully constructed novel TriBAFF-CAR-T cells to eliminate BAFFR-bearing and CD19 antigen loss in hematological tumor cells.

Novel CD37, Humanized CD37 and Bi-Specific Humanized CD37-CD19 CAR-T Cells Specifically Target Lymphoma

Simple Summary

Chimeric antigen receptor (CAR) T cell therapy represents a major advancement in cancer treatment. Recently, FDA approved CAR-T cells directed against the CD19 protein for treatment of leukemia and lymphoma. In spite of impressive clinical responses with CD19-CAR-T cells, some patients demonstrate disease relapse due to either antigen loss, cancer heterogeneity or other mechanisms. Novel CAR-T cells and targets are important for the field. This report describes novel CD37, humanized CD37 and bispecific humanized CD37-CD19-CAR-T cells targeting both CD37 and CD19. The study demonstrates that these novel CAR-T cells specifically targeted either CD37 positive or CD37 and CD19-positive cells with endogenous and exogenous protein expression and provides a basis for future clinical studies.

Abstract

CD19 and CD37 proteins are highly expressed in B-cell lymphoma and have been successfully targeted with different monotherapies, including chimeric antigen receptor (CAR)-T cell therapy. The goal of this study was to target lymphoma with novel CD37, humanized CD37, and bi-specific humanized CD37-CD19 CAR-T cells. A novel mouse monoclonal anti-human CD37 antibody (clone 2B8D12F2D4) was generated with high binding affinity for CD37 antigen (KD = 1.6 nM). The CD37 antibody specifically recognized cell surface CD37 protein in lymphoma cells and not in multiple myeloma or other types of cancer. The mouse and humanized CD37-CAR-T cells specifically killed Raji and CHO-CD37 cells and secreted IFN-gamma. In addition, we generated bi-specific humanized hCD37-CD19 CAR-T cells that specifically killed Raji cells, CHO-CD37, and Hela-CD19 cells and did not kill control CHO or Hela cells. Moreover, the hCD37-CD19 CAR-T cells secreted IFN-gamma against CD37-positive and CD19-positive target CHO-CD37, Hela-CD19 cells, respectively, but not against CD19 and CD37-negative parental cell line. The bi-specific hCD37-CD19 significantly inhibited Raji xenograft tumor growth and prolonged mouse survival in NOD scid gamma mouse (NSG) mouse model. This study demonstrates that novel humanized CD37 and humanized CD37-CD19 CAR-T cells specifically targeted either CD37 positive or CD37 and CD19-positive cells and provides a basis for future clinical studies.

Novel therapeutic options for radioiodine-refractory thyroid cancer: redifferentiation and beyond

PURPOSE OF REVIEW

Radioiodine-refractory thyroid cancers represent the main cause of thyroid cancer-related death. At present, targeted therapies with multikinase inhibitors represent a unique therapeutic tool, though they have limited benefit on patient survival and severe drug-associated adverse events. This review summarizes current treatment strategies for radioiodine-refractory thyroid cancer and focuses on novel approaches to redifferentiate thyroid cancer cells to restore responsiveness to radioiodine administration.

RECENT FINDINGS

We summarize and discuss recent clinical trial findings and early data from real-life experiences with multikinase-inhibiting drugs. Possible alternative strategies to traditional redifferentiation are also discussed.

SUMMARY

The current review focuses primarily on the major advancements in the knowledge of the pathophysiology of iodine transport and metabolism and the genetic and epigenetic alterations occurring in thyroid neoplasia as described using preclinical models. Results of clinical studies employing new compounds to induce thyroid cancer cell redifferentiation by acting against specific molecular targets are also discussed. Finally, we describe the current scenario emerging from such findings as well as future perspectives.

Current Challenges in Providing Good Leukapheresis Products for Manufacturing of CAR-T Cells for Patients with Relapsed/Refractory NHL or ALL

Background: T lymphocyte collection through leukapheresis is an essential step for chimeric antigen receptor T (CAR-T) cell therapy. Timing of apheresis is challenging in heavily pretreated patients who suffer from rapid progressive disease and receive T cell impairing medication. Methods: A total of 75 unstimulated leukaphereses were analyzed including 45 aphereses in patients and 30 in healthy donors. Thereof, 41 adult patients with Non-Hodgkin’s lymphoma (85%) or acute lymphoblastic leukemia (15%) underwent leukapheresis for CAR-T cell production. Results: Sufficient lymphocytes were harvested from all patients even from those with low peripheral lymphocyte counts of 0.18/nL. Only four patients required a second leukapheresis session. Leukapheresis products contained a median of 98 × 10⁸ (9 - 341 × 10⁸) total nucleated cells (TNC) with 38 × 10⁸ (4 - 232 × 10⁸) CD3+ T cells. Leukapheresis products from healthy donors as well as from patients in complete remission were characterized by high TNC and CD3+ T lymphocyte counts. CAR-T cell products could be manufactured for all but one patient. Conclusions: Sufficient yield of lymphocytes for CAR-T cell production is feasible also for patients with low peripheral blood counts. Up to 12–15 L blood volume should be processed in patients with absolute lymphocyte counts ≤ 1.0/nL.

Feasibility of leukapheresis for CAR T-cell production in heavily pre-treated pediatric patients

BACKGROUND

Autologous CD19 chimeric-antigen receptor (CAR) T-cells are an effective salvage therapy for patients with relapsed or refractory B cell malignancies. The essential first step in the production is the collection of mature lymphocytes through leukapheresis. It is a challenging procedure given the fact patients are heavily pretreated and the special considerations of pediatric apheresis.

METHODS

We analyzed the data of leukapheresis outcome for CAR T production in a phase 1b/2 clinical trial enrolling 34 children, adolescents and young adults with relapsed or refractory B-cell malignancies.

RESULTS

All patients underwent a single leukapheresis. Given a short production time for CAR T-cells, most patients received bridging therapy prior to apheresis. Leukapheresis was performed using peripheral venous access in the majority (82%) of patients, and the remainder required arterial line or central venous access. T-cell collection efficiency (CE) was variable with a median of 18%. No apheresis-related adverse events were noted, and all procedures were successful but two: one resulting in lower than target dose (1 × 10⁶ CAR + cells/kg) and the other in failure of CAR T-cell production.

CONCLUSIONS

Collection of sufficient T-cells in heavily pretreated pediatric patients via a single apheresis procedure is feasible even with relatively low T-cell CE.

Chimeric antigen receptor T cell therapy comes to clinical practice

Adoptive cellular therapy with chimeric antigen receptor T cells (car-ts) has recently received approval from Health Canada and the U.S. Food and Drug Administration after remarkable and durable remissions were seen in children with recurrent or refractory leukemia and adults with non-Hodgkin lymphoma-responses that were so impressive that a shift in the paradigm of care has now occurred for children with acute lymphoblastic leukemia. The concept behind car-t immunotherapy is that modification of a patient's own T cells to facilitate their localization to the cancer cell, with subsequent activation of the T cell effector mechanism and proliferation, will result in targeted killing of cancer cells. The car-ts are a novel drug in that the starting material for the manufacture of the car-t product comes from the patient, whose viable T cells are then genetically modified. Thus, collaboration is needed between the pharmaceutical companies, which must meet good manufacturing standards for each patient's unique product, and the treating sites. For regulators and health authorities, this new class of drugs requires new paradigms for assessment and approval. Treatments with car-ts require that institutions address unique logistics requirements and management of novel toxicities. The Hospital for Sick Children has had early experience with both the licensing of clinical trials and the introduction of the first commercial product. Here, we provide an overview of basic concepts and treatment, with caveats drawn from what we have learned thus far in bringing this new therapy to the clinical front line.

CAR-T Cells for Cancer Treatment: Current Design and Next Frontiers

Immunotherapy has been growing in the past decade as a therapeutic alternative for cancer treatment. In this chapter, we deal with CAR-T cells, genetically engineered autologous T cells to express a chimeric receptor specific for an antigen expressed on tumor cell surface. While this type of personalized therapy is revolutionizing cancer treatment, especially B cell malignancies, it has some challenging limitations. Here, we discuss the basic immunological and technological aspects of CAR-T cell therapy, the limitations that have compromised its efficacy and safety, and the current proposed strategies to overcome these limitations, thereby allowing for greater therapeutic application of CAR-T cells.

Back-to-Germline (B2G) Procedure for Antibody Devolution

Bispecific antibodies (bsAbs) with avidity-enhanced specificity can be used to address target cells with increased specificity, ideally binding efficiently to cells that express two cognate antigens, yet not to cells that express only one of those. Building blocks required to generate such bsAbs are binders that recognize the two antigens with high specificity yet with various (including very low monovalent) affinities. The herein described ‘back-to-germline’ (B2G) procedure defines such derivatives. It converts parent antibodies with high specificity to derivatives that retain specificity but modulate affinity. The approach defines mutations to be introduced into antibody complementarity-determining regions (CDRs) regions without requiring structures of antibody-antigen complexes. Instead, it reverses the B-cell maturation process that increases affinities, with preference on CDR residues with high antigen contact probability. Placing germline residues at those positions generates VH and VL domains and Fv-combinations thereof that retain specificities but are ‘de-matured’ to different degrees. De-maturation influences on-rates and off-rates, and can produce entities with extremely low affinity for which binding can only be detected in bivalent formats. A comparison with alanine replacement in CDRs (so far, the most frequently applied technology) indicates that B2G may be more reliable/predictable without introduction of stickiness or poly-reactivity. The applicability for generating sets of affinity-modulated monospecific variants is exemplarily shown for antibodies that bind CD138, Her2/neu, and EGFR.

Mechanisms of resistance to CAR T cell therapy

The successes with chimeric antigen receptor (CAR) T cell therapy in early clinical trials involving patients with pre-B cell acute lymphoblastic leukaemia (ALL) or B cell lymphomas have revolutionized anticancer therapy, providing a potentially curative option for patients who are refractory to standard treatments. These trials resulted in rapid FDA approvals of anti-CD19 CAR T cell products for both ALL and certain types of B cell lymphoma - the first approved gene therapies in the USA. However, growing experience with these agents has revealed that remissions will be brief in a substantial number of patients owing to poor CAR T cell persistence and/or cancer cell resistance resulting from antigen loss or modulation. Furthermore, the initial experience with CAR T cells has highlighted challenges associated with manufacturing a patient-specific therapy. Understanding the limitations of CAR T cell therapy will be critical to realizing the full potential of this novel treatment approach. Herein, we discuss the factors that can preclude durable remissions following CAR T cell therapy, with a primary focus on the resistance mechanisms that underlie disease relapse. We also provide an overview of potential strategies to overcome these obstacles in an effort to more effectively incorporate this unique therapeutic strategy into standard treatment paradigms.

Factors affecting lymphocyte collection efficiency for the manufacture of chimeric antigen receptor T cells in adults with B-cell malignancies

BACKGROUND

The clinical and procedural parameters that affect the optimal collection of lymphocytes for the production of chimeric antigen receptor (CAR) T cells remain undefined but are increasingly important, as commercial products are now available. We evaluated determinants of low lymphocyte collection efficiency (CE) and the rate of successful CAR T-cell manufacture in middle-aged and older adults with advanced B-cell malignancies.

STUDY DESIGNS AND METHODS

Mononuclear cell collections using two apheresis platforms (COBE Spectra and Spectra Optia, Terumo BCT) from patients participating in a CD19-directed CAR T-cell therapy trial were reviewed. Patient- and disease-specific factors, peripheral blood counts, apheresis parameters, and product cell counts were analyzed to determine effects on lymphocyte CE.

RESULTS

Ninety-two apheresis events from patients with acute lymphocytic leukemia (ALL) (n = 28), chronic lymphocytic leukemia (n = 18), and non-Hodgkin lymphoma (n = 46) were available for analysis. Forty-one collections (45%) had a lymphocyte CE of <40%. On multivariable analysis, age (every 10-year increase, odds ratio [OR] = 1.51; p = 0.034), disease type (chronic lymphocytic leukemia vs. ALL, OR = 0.24; p = 0.052; non-Hodgkin lymphoma vs. ALL, OR = 0.20; p = 0.009) and precollection platelets (every 10 × 10³ /μL increase, OR = 1.07; p = 0.005) were appreciably associated with a lymphocyte CE of <40%. No major apheresis complications occurred.

CONCLUSIONS

Lymphocyte collection at our center was well tolerated and 100% successful in manufacturing CD19-directed CAR T cells from adult patients with B-cell malignancies despite low CE in some patients. A diagnosis of ALL, advancing age, and higher preapheresis platelet counts were observed to be associated with low CE.

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.

Chimeric Antigen Receptor T-cell (CAR T) Therapy for Hematologic and Solid Malignancies: Efficacy and Safety-A Systematic Review with Meta-Analysis

Chimeric antigen receptors T cells (CAR T) had been used for treating various tumor patients in clinic, and owned an incredible efficacy in part of malignancies. However, CAR T therapy remains controversial due to doubts about its efficacy and safety in the clinical treatment of various malignancies. A total of 997 tumor patients from 52 studies were included in this review. Eligible studies were searched and reviewed from the databases of PubMed, Web of Science, Wanfang and Clinicaltrials.gov. Then meta-analysis and subgroup analysis were used to investigate the overall response rate (ORR), complete response rate (CRR), common side effect rate (CSER) and relapse rate (RR) of CAR T therapy for patients in clinical researches, respectively. The results further confirmed that CAR T therapy had a higher response rate for hematologic malignancies. More importantly, CAR T therapy had a higher CSER in patients with hematologic malignancies, and it had a similar RR in patients with different malignancies. Cell cultured without the addition of IL-2 and total administration less than 10⁸ cells were recommended. This study offers a reference for future research regarding the application in solid and hematologic malignancies, side effects and relapse, and even the production processes of CAR T cells.

Immunotherapy Using Chimeric Antigen Receptor-Engineered T Cells: A Novel Cellular Therapy with Important Implications for the Clinical Laboratory

BACKGROUND

We have entered a new era of cancer therapy, with a number of immune-based therapies already used clinically as a standard of care. Adoptive cellular immunotherapy using T cells genetically modified with chimeric antigen receptors (CAR-T cells) represents a novel therapeutic approach. CAR-T cells have produced clinical responses in B-cell malignancies that are otherwise refractory to conventional therapies. Two CAR-T cell therapies obtained regulatory approval in 2017, with many more of these therapies under clinical development.

CONTENT

This review focuses on the current state of adoptive cellular immunotherapy, specifically CAR-T cells, in the clinic and how this therapy differs from traditional small molecule and biologic therapies. Areas in which the clinical laboratory is affected by these novel therapies are discussed. Opportunities for the clinical laboratory to help guide these therapies are also highlighted.

SUMMARY

The clinical laboratory will play an integral role in the care of patients undergoing adoptive cellular therapy with engineered T cells. There are many ways that this new therapeutic approach affects the clinical laboratory, and the clinical laboratory will likely play a critical role in managing patients that are treated with CAR-T cell therapy.