Regulation of advanced therapy medicinal products in Europe and the role of academia

Background aimsAdvanced therapy medicinal products (ATMP) are gene therapy, somatic cell therapy or tissue-engineered products regulated under (EC) No. 1394/2007 to ensure their free movement within the European Union while guaranteeing the highest level of health protection for patients. Academic good manufacturing practice (GMP) centers are major contributors in the development of ATMPs and this study assessed the impact of regulations on them.MethodsEuropean academic and non-industrial facilities (n = 747) were contacted, and a representative sample of 50 replied to a detailed questionnaire. Experienced centres were further selected in every Member State (MS) for semi-structured interviews. Indicators of ATMP production and development success were statistically assessed, and opinions about directive implementation were documented.ResultsFacilities experienced in manufacturing cell therapy transplant products are the most successful in developing ATMPs. New centres lacking this background struggle to enter the field, and there remains a shortage of facilities in academia participating in translational research. This is compounded by heterogeneous implementation of the regulations across MS.ConclusionsGMP facilities successfully developing ATMPs are present in all MS. However, the implementation of regulations is heterogeneous between MS, with substantial differences in the definition of ATMPs and in the approved manufacturing environment. The cost of GMP compliance is underestimated by research funding bodies. This is detrimental to development of new ATMPs and commercialization of any that are successful in early clinical trials. Academic GMP practitioners should strengthen their political visibility and contribute to the development of functional and effective European Union legislation in this field.     

Advanced therapy medicinal product manufacturing under the hospital exemption and other exemption pathways in seven European Union countries

Background aimsAs part of the advanced therapy medicinal product (ATMP) regulation, the hospital exemption (HE) was enacted to accommodate manufacturing of custom-made ATMPs for treatment purposes in the European Union (EU). However, how the HE pathway has been used in practice is largely unknown.MethodsUsing a survey and interviews, we provide the product characteristics, scale and motivation for ATMP manufacturing under HE and other, non-ATMP-specific exemption pathways in seven European countries.ResultsResults show that ATMPs were manufactured under HE by public facilities located in Finland, Germany, Italy and the Netherlands, which enabled availability of a modest number of ATMPs (n = 12) between 2009 and 2017. These ATMPs were shown to have close proximity to clinical practice, and manufacturing was primarily motivated by clinical needs and clinical experience. Public facilities used HE when patients could not obtain treatment in ongoing or future trials. Regulatory aspects motivated (Finland, Italy, the Netherlands) or limited (Belgium, Germany) HE utilization, whereas financial resources generally limited HE utilization by public facilities. Public facilities manufactured other ATMPs (n = 11) under named patient use (NPU) between 2015 and 2017 and used NPU in a similar fashion as HE. The scale of manufacturing under HE over 9 years was shown to be rather limited in comparison to manufacturing under NPU over 3 years. In Germany, ATMPs were mainly manufactured by facilities of private companies under HE.ConclusionsThe HE enables availability of ATMPs with close proximity to clinical practice. Yet in some countries, HE provisions limit utilization, whereas commercial developments could be undermined by private HE licenses in Germany. Transparency through a public EU-wide registry and guidance for distinguishing between ATMPs that are or are not commercially viable as well as public-private engagements are needed to optimize the use of the HE pathway and regulatory pathways for commercial development in a complementary fashion.     

Patient access to and ethical considerations of the application of the European Union hospital exemption rule for advanced therapy medicinal products

Hospital exemption (HE) is a regulated pathway that allows the use of advanced therapy medicinal products (ATMPs) within the European Union (EU) under restrictive conditions overseen by national medicine agencies. In some EU countries, HE is granted for ATMPs with no demonstrated safety and efficacy; therefore, they are equivalent to investigational drugs. In other countries, HE is granted for ATMPs with demonstrated quality, safety and efficacy and for which centralized marketing authorization has not been requested. The Committee on the Ethics of Cell and Gene Therapy of the International Society for Cell & Gene Therapy reflects here on the ethical issues concerning HE application from the perspective of the patient, including risk–benefit balance, accessibility and transparency, while providing evidence that HE must not be regarded as a conduit for unproven and unethical ATMP-based interventions. Indeed, HE represents a legal instrument under which a patient's need for access to novel ATMPs is reconciled with ethics. Moreover, for some unmet medical needs, HE is the only pathway for accessing innovative ATMPs. Nonetheless, HE harmonization across EU Member States and limitations of ATMP use under the HE rule when similar products have already been granted centralized marketing authorization to avoid a parallel regulatory pathway are controversial issues whose political and economic consequences are beyond the scope of this review. Finally, the institution of an EU registry of HE applications and outcomes represents a priority to improve transparency, reduce patient risks, increase efficiency of health systems, facilitate company awareness of business opportunities and boost progressive entry of ATMPs into the therapeutic repertoire of health systems.     

A comprehensive report of long-term stability data for a range ATMPs: A need to develop guidelines for safe and harmonized stability studies

Background aimsAdvanced therapy medicinal products (ATMPs) are novel drugs based on genes, cells or tissues developed to treat many different diseases. Stability studies of each new ATMP need to be performed to define its shelf life and guarantee efficacy and safety upon infusion, and these are presently based on guidelines originally drafted for standard pharmaceutical drugs, which have properties and are stored in conditions quite different from cell products. The aim of this report is to provide evidence-based information for stability studies on ATMPs that will facilitate the interlaboratory harmonization of practices in this area.MethodsWe have collected and analyzed the results of stability studies on 19 different cell-based experimental ATMPs, produced by five authorized cell factories forming the Lombardy “Plagencell network” for use in 36 approved phase I/II clinical trials; most were cryopreserved and stored in liquid nitrogen vapors for 1 to 13 years.ResultsThe cell attributes collected in stability studies included cell viability, immunophenotype and potency assays, in particular immunosuppression, cytotoxicity, cytokine release and proliferation/differentiation capacity. Microbiological attributes including sterility, endotoxin levels and mycoplasma contamination were also analyzed. All drug products (DPs), cryopreserved in various excipients containing 10% DMSO and in different primary containers, were very stable long term at <–150°C and did not show any tendency for diminished viability or efficacy for up to 13.5 years.ConclusionsOur data indicate that new guidelines for stability studies, specific for ATMPs and based on risk analyses, should be drafted to harmonize practices, significantly reduce the costs of stability studies without diminishing safety. Some specific suggestions are presented in the discussion.     

Comparison of new Brazilian legislation for the approval of advanced therapy medicinal products with existing systems in the USA,European Union and Japan

Background aimsAdvanced therapy medicinal products (ATMPs) are a class of biological products for human use that are based on genes, cells and tissues. The first ATMP received marketing authorization in Europe in 2009, whereas Brazil granted the first authorization in 2020. The objective of this study was to compare the regulatory models adopted by Brazil, the USA, Japan and the European Union, which comprise the member countries of the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use, with regard to the marketing authorization of ATMPs.MethodsThe authors performed a review of the scientific literature and official documents of the regulatory agencies in the aforementioned countries.ResultsThe legislation and regulatory guidelines adopted by the regulatory agencies exhibit similarities and differences. It was not possible to assess whether these differences can be translated into divergent final recommendations by regulatory authorities upon a request for marketing authorization.ConclusionsIn the future, it will be appropriate to start a progressive process of harmonization between these agencies in terms of terminology, legal recommendations and characterization requirements. This is particularly important for emerging countries such as Brazil. In this sense, some measures can be taken to achieve alignment between regulators.     

Comparison of regulatory pathways for the approval of advanced therapies in the European Union and the United States

Background aimsRegulatory agencies in the European Union (EU) and in the United States of America (USA) have adapted and launched regulatory pathways to accelerate patient access to innovative therapies, such as advanced therapy medicinal products (ATMPs). The aim of this study is to analyze similarities and differences between regulatory pathways followed by the approved ATMPs in both regions.MethodsA retrospective analysis of the ATMPs approved by EU and US regulatory agencies was carried out until May 31, 2020. Data were collected on the features and timing of orphan drug designation (ODD), scientific advice (SA), expedited program designation (EP), marketing authorization application (MAA) and marketing authorization (MA) for both regions.ResultsIn the EU, a total of fifteen ATMPs were approved (eight gene therapies, three somatic cell therapies, three tissue-engineered products and one combined ATMP), whereas in the USA, a total of nine were approved (five gene therapies and four cell therapies); seven of these were authorized in both regions. No statistical differences were found in the mean time between having the ODD or EP granted and the start of the pivotal clinical trial or MAA in the EU and USA, although the USA required less time for MAA assessment than the EU (mean difference, 5.44, P = 0.012). The MAA assessment was shorter for those products with a PRIME or breakthrough designation.. No differences were found in the percentage of ATMPs with expedited MAA assessment between the EU and the USA (33.3% versus 55.5%, respectively, P = 0.285) or in the time required for the MAA expedited review (mean difference 4.41, P = 0.105). Approximately half of the products in both regions required an Advisory Committee during the MAA review, and 60% required an oral explanation in the EU. More than half of the approved ATMPs (67% and 55.55% in the EU and the USA, respectively) were granted an ODD, 70% by submitting preliminary clinical data in the EU. The mean number of SA and protocol assistance per product conducted by the European Medicines Agency was 1.71 and 3.75, respectively, and only 13% included parallel advice with health technology assessment bodies. A total of 53.33% of the products conducted the first SA after the pivotal clinical study had started, reporting more protocol amendments. Finally, of the seven ATMPs authorized in both regions, the type of MA differed for only two ATMPs (28.6%), and four out of eight products non-commercialized in the USA had a non-standard MA in the EU.ConclusionsThe current approved ATMPs mainly target orphan diseases. Although EU and US regulatory procedures may differ, the main regulatory milestones reached by the approved ATMPs are similar in both regions, with the exception of the time for MAA evaluation, the number of authorized products in the regions and the type of authorization for some products. More global regulatory convergence might further simplify and expedite current ATMP development in these regions.     

Business oriented EU human cell and tissue product legislation will adversely impact Member States’ health care systems

The transplantation of conventional human cell and tissue grafts, such as heart valve replacements and skin for severely burnt patients, has saved many lives over the last decades. The late eighties saw the emergence of tissue engineering with the focus on the development of biological substitutes that restore or improve tissue function. In the nineties, at the height of the tissue engineering hype, industry incited policymakers to create a European regulatory environment, which would facilitate the emergence of a strong single market for tissue engineered products and their starting materials (human cells and tissues). In this paper we analyze the elaboration process of this new European Union (EU) human cell and tissue product regulatory regime—i.e. the EU Cell and Tissue Directives (EUCTDs) and the Advanced Therapy Medicinal Product (ATMP) Regulation and evaluate its impact on Member States’ health care systems. We demonstrate that the successful lobbying on key areas of regulatory and policy processes by industry, in congruence with Europe’s risk aversion and urge to promote growth and jobs, led to excessively business oriented legislation. Expensive industry oriented requirements were introduced and contentious social and ethical issues were excluded. We found indications that this new EU safety and health legislation will adversely impact Member States’ health care systems; since 30 December 2012 (the end of the ATMP transitional period) there is a clear threat to the sustainability of some lifesaving and established ATMPs that were provided by public health institutions and small and medium-sized enterprises under the frame of the EUCTDs. In the light of the current economic crisis it is not clear how social security systems will cope with the inflation of costs associated with this new regulatory regime and how priorities will be set with regard to reimbursement decisions. We argue that the ATMP Regulation should urgently be revised to focus on delivering affordable therapies to all who are in need of them and this without necessarily going to the market. The most rapid and elegant way to achieve this would be for the European Commission to publish an interpretative document on “placing on the market of ATMPs,” which keeps tailor-made and niche ATMPs outside of the scope of the medicinal product regulation.     

A hub-and-spoke model to deliver effective access to chimeric antigen receptor T-cell therapy in a public health network: the Catalan Blood and Tissue Bank experience

Background aimsTo describe and analyze whether a hub-and-spoke organizational model could efficiently provide access to chimeric antigen receptor (CAR) T-cell therapy within a network of academic hospitals and address the growing demands of this complex and specialized activity.MethodsThe authors performed a retrospective evaluation of activity within the Catalan Blood and Tissue Bank network, which was established for hematopoietic stem cell transplantation to serve six CAR T-cell programs in academic hospitals of the Catalan Health Service. Procedures at six hospitals were followed from 2016 to 2021. Collection shipments of starting materials, CAR T-cell returns for storage and infusions for either clinical trials or commercial use were evaluated.ResultsA total of 348 leukocytapheresis procedures were performed, 39% of which were delivered fresh and 61% of which were cryopreserved. The network was linked to seven advanced therapy medicinal product manufacturers. After production, 313 CAR T-cell products were shipped back to the central cryogenic medicine warehouse located in the hub. Of the units received, 90% were eventually administered to patients. A total of 281 patients were treated during this period, 45% in clinical trials and the rest with commercially available CAR T-cell therapies.ConclusionsA hub-and-spoke organizational model based on an existing hematopoietic stem cell transplantation program is efficient in incorporating CAR T-cell therapy into a public health hospital network. Rapid access and support of growing activity enabled 281 patients to receive CAR T cells during the study period.     

Definition and application of good manufacturing process-compliant production of CEA-specific chimeric antigen receptor expressing T-cells for phase I/II clinical trial

Adoptive cell therapy employing gene-modified T-cells expressing chimeric antigen receptors (CARs) has shown promising preclinical activity in a range of model systems and is now being tested in the clinical setting. The manufacture of CAR T-cells requires compliance with national and European regulations for the production of medicinal products. We established such a compliant process to produce T-cells armed with a first-generation CAR specific for carcinoembryonic antigen (CEA). CAR T-cells were successfully generated for 14 patients with advanced CEA⁺ malignancy. Of note, in the majority of patients, the defined procedure generated predominantly CD4⁺ CAR T-cells with the general T-cell population bearing an effector–memory phenotype and high in vitro effector function. Thus, improving the process to generate less-differentiated T-cells would be more desirable in the future for effective adoptive gene-modified T-cell therapy. However, these results confirm that CAR T-cells can be generated in a manner compliant with regulations governing medicinal products in the European Union.     

Ex vivo-expanded highly pure ABCB5+ mesenchymal stromal cells as Good Manufacturing Practice-compliant autologous advanced therapy medicinal product for clinical use: process validation and first in-human data

Background aimMesenchymal stromal cells (MSCs) hold promise for the treatment of tissue damage and injury. However, MSCs comprise multiple subpopulations with diverse properties, which could explain inconsistent therapeutic outcomes seen among therapeutic attempts. Recently, the adenosine triphosphate-binding cassette transporter ABCB5 has been shown to identify a novel dermal immunomodulatory MSC subpopulation.MethodsThe authors have established a validated Good Manufacturing Practice (GMP)-compliant expansion and manufacturing process by which ABCB5⁺ MSCs can be isolated from skin tissue and processed to generate a highly functional homogeneous cell population manufactured as an advanced therapy medicinal product (ATMP). This product has been approved by the German competent regulatory authority to be tested in a clinical trial to treat therapy-resistant chronic venous ulcers.ResultsAs of now, 12 wounds in nine patients have been treated with 5 × 10⁵ autologous ABCB5⁺ MSCs per cm² wound area, eliciting a median wound size reduction of 63% (range, 32–100%) at 12 weeks and early relief of pain.ConclusionsThe authors describe here their GMP- and European Pharmacopoeia-compliant production and quality control process, report on a pre-clinical dose selection study and present the first in-human results. Together, these data substantiate the idea that ABCB5⁺ MSCs manufactured as ATMPs could deliver a clinically relevant wound closure strategy for patients with chronic therapy-resistant wounds.     

Decisional tool for cost of goods analysis of bioartificial liver devices for routine clinical use

Background aimsBioartificial liver devices (BALs) are categorized as advanced therapy medicinal products (ATMPs) with the potential to provide temporary liver support for liver failure patients. However, to meet commercial demands, next-generation BAL manufacturing processes need to be designed that are scalable and financially feasible. The authors describe the development and application of a process economics decisional tool to determine the cost of goods (COG) of alternative BAL process flowsheets across a range of industrial scales.MethodsThe decisional tool comprised an information database linked to a process economics engine, with equipment sizing, resource consumption, capital investment and COG calculations for the whole bioprocess, from cell expansion and encapsulation to fluidized bed bioreactor (FBB) culture to cryopreservation and cryorecovery. Four different flowsheet configurations were evaluated across demands, with cell factories or microcarriers in suspension culture for the cell expansion step and single-use or stainless steel technology for the FBB culture step.ResultsThe tool outputs demonstrated that the lowest COG was achieved with microcarriers and stainless steel technology independent of the annual demand (1500–30 000 BALs/year). The analysis identified the key cost drivers were parameters impacting the medium volume and cost.ConclusionsThe tool outputs can be used to identify cost-effective and scalable bioprocesses early in the development process and minimize the risk of failing to meet commercial demands due to technology choices. The tool predictions serve as a useful benchmark for manufacturing ATMPs.     

Good Manufacturing Practices (GMP) manufacturing of advanced therapy medicinal products: a novel tailored model for optimizing performance and estimating costs

Background aimsAdvanced therapy medicinal products (ATMP) have gained considerable attention in academia due to their therapeutic potential. Good Manufacturing Practice (GMP) principles ensure the quality and sterility of manufacturing these products. We developed a model for estimating the manufacturing costs of cell therapy products and optimizing the performance of academic GMP-facilities.MethodsThe “Clean-Room Technology Assessment Technique” (CTAT) was tested prospectively in the GMP facility of BCRT, Berlin, Germany, then retrospectively in the GMP facility of the University of California-Davis, California, USA. CTAT is a two-level model: level one identifies operational (core) processes and measures their fixed costs; level two identifies production (supporting) processes and measures their variable costs. The model comprises several tools to measure and optimize performance of these processes. Manufacturing costs were itemized using adjusted micro-costing system.ResultsCTAT identified GMP activities with strong correlation to the manufacturing process of cell-based products. Building best practice standards allowed for performance improvement and elimination of human errors. The model also demonstrated the unidirectional dependencies that may exist among the core GMP activities. When compared to traditional business models, the CTAT assessment resulted in a more accurate allocation of annual expenses. The estimated expenses were used to set a fee structure for both GMP facilities. A mathematical equation was also developed to provide the final product cost.ConclusionsCTAT can be a useful tool in estimating accurate costs for the ATMPs manufactured in an optimized GMP process. These estimates are useful when analyzing the cost-effectiveness of these novel interventions.     

An assessment of the hospital exemption landscape across European Member States: regulatory frameworks,use and impact

The hospital exemption (HE) (Article 28(2) of Regulation (EC) No 1394/2007; the “ATMP Regulation”) rule allows the invaluable opportunity to provide patients with access to innovative, potentially life-saving treatments in situations of unmet clinical need. Unlicensed, developmental advanced therapy medicinal products (ATMPs) - cell-, gene- or tissue-based therapies - can be used to treat patients under certain conditions. Such products should be produced on a non-routine basis, custom-made for an individual patient under the responsibility of the requesting physician, for use in a hospital setting within the same Member State in which they are manufactured. The HE rule, and the specific requirements permitting its use, is further regulated at the Member State level, which has led to divergence in the implementation of HE across the European Union (EU). As a result, HE use varies significantly across Member States depending on their respective national legal implementation, policy makers’ interpretation of HE, clarity of guidance at the national level, reimbursement opportunities and level of ATMP research and development activities carried out by academic and commercial organizations. With important variations in how quality, safety and efficacy standards are implemented and controlled across EU Member States for ATMPs provided via the HE rule and a lack of transparency around its use, the HE rule draws concern around its potential impact on public health. In this article, the authors report results of a legal analysis of the implementation of HE across the UK, France, Germany, Italy, Spain, Poland and the Netherlands and research findings on its current utilization, highlighting divergences across countries as well as gaps in legislation and control in these countries. The significance of these divergences and the differing levels of enforcement are discussed as well as their associated impact on patients, industry and health care professionals.     

Label-free in vitro assays predict the potency of anti-disialoganglioside chimeric antigen receptor T-cell products

Background aimsChimeric antigen receptor (CAR) T cells have demonstrated remarkable efficacy against hematological malignancies; however, they have not experienced the same success against solid tumors such as glioblastoma (GBM). There is a growing need for high-throughput functional screening platforms to measure CAR T-cell potency against solid tumor cells.MethodsWe used real-time, label-free cellular impedance sensing to evaluate the potency of anti-disialoganglioside (GD2) targeting CAR T-cell products against GD2+ patient-derived GBM stem cells over a period of 2 days and 7 days in vitro. We compared CAR T products using two different modes of gene transfer: retroviral transduction and virus-free CRISPR-editing. Endpoint flow cytometry, cytokine analysis and metabolomics data were acquired and integrated to create a predictive model of CAR T-cell potency.ResultsResults indicated faster cytolysis by virus-free CRISPR-edited CAR T cells compared with retrovirally transduced CAR T cells, accompanied by increased inflammatory cytokine release, CD8+ CAR T-cell presence in co-culture conditions and CAR T-cell infiltration into three-dimensional GBM spheroids. Computational modeling identified increased tumor necrosis factor α concentrations with decreased glutamine, lactate and formate as being most predictive of short-term (2 days) and long-term (7 days) CAR T cell potency against GBM stem cells.ConclusionsThese studies establish impedance sensing as a high-throughput, label-free assay for preclinical potency testing of CAR T cells against solid tumors.     

Prognostic impact of peripheral eosinophil counts in patients with diffuse large B-cell lymphoma receiving chimeric antigen receptor T-cell therapy

Background aimsChimeric antigen receptor (CAR) T-cell therapy is a breakthrough treatment for patients with relapsed or refractory diffuse large B-cell lymphoma. However, many patients do not achieve remission or relapse after remission. Previous studies have demonstrated that eosinophils have synergistic anti-tumor effects with CD8⁺T cells and pre-CAR T-eosinophil counts are associated with the efficacy of CAR T cells.MethodsWe retrospectively analyzed the eosinophil counts of patients with diffuse large B-cell lymphoma and found it changed remarkably pre- and post-CAR T-cell therapy.ResultsPatients who achieved complete remission after CAR T-cell infusion had greater post-CAR T-eosinophil counts than those who did not. Kaplan–Meier curves showed that patients with greater eosinophil counts during the second month after CAR T-cell infusion had superior progression-free survival and overall survival compared with those with lower eosinophil counts.ConclusionsFor patients who responded to CAR T-cell therapy, eosinophil counts also can be used to predict 6-month duration of response. In conclusion, the post-CAR T-eosinophil count is associated with the prognosis of patients treated with CAR T-cell therapy and can be used to clinically identify patients who can achieve longer remission after CAR T-cell infusion.     

Establishing a robust chimeric antigen receptor T-cell therapy program in Australia: the Royal Prince Alfred Hospital experience

>himeric antigen receptor (CAR) T-cell therapy is a novel approved cancer treatment that has shown remarkable efficacy in the treatment of patients with relapsed leukemia and lymphoma. Implementation of CAR T-cell therapy in a hospital setting requires careful and detailed planning because of the complexities in delivering this specialist service. A multi-disciplinary approach with dedicated funding is required to meet clinical, scientific, logistic and regulatory requirements. Tisagenlecleucel was the first approved CAR T-cell therapy in Australia. The treatment has been made available to Australian patients in specialist public hospitals through federal and state funding. Royal Prince Alfred Hospital (RPAH) is one of Australia's oldest tertiary referral public health care institutions and was approved for the provision of CAR T-cell therapy service in 2019. A multi-disciplinary clinical program has been established for the collection and cryopreservation of donor cells shipped for manufacturing as well as for the receipt, storage and administration of CAR T-cell therapy and patient management. The program encompasses a Therapeutic Goods Administration-accredited apheresis unit and a state-of-the-art facility for cell processing, cryopreservation and storage. The program's clinical expertise extends to hematology, oncology, intensive care, pharmacy, neurology and radiology services with direct experience in managing patients receiving CAR T-cell therapies. The introduction of CAR T-cell therapies at RPAH was a complex undertaking facilitated by the existing infrastructure and clinical expertise.     

Digital polymerase chain reaction strategies for accurate and precise detection of vector copy number in chimeric antigen receptor T-cell products

Background aimsVector copy number (VCN), an average quantification of transgene copies unique to a chimeric antigen receptor (CAR) T-cell product, is a characteristic that must be reported prior to patient administration, as high VCN increases the risk of insertional mutagenesis. Historically, VCN assessment in CAR T-cell products has been performed via quantitative polymerase chain reaction (qPCR). qPCR is reliable along a broad range of concentrations, but quantification requires use of a standard curve and precision is limited. Digital PCR (dPCR) methods were developed for absolute quantification of target sequences by counting nucleic acid molecules encapsulated in discrete, volumetrically defined partitions. Advantages of dPCR compared with qPCR include simplicity, reproducibility, sensitivity and lack of dependency on a standard curve for definitive quantification. In the present study, the authors describe a dPCR assay developed for analysis of the novel bicistronic CD19 × CD22 CAR T-cell construct.MethodsThe authors compared the performance of the dPCR assay with qPCR on both the QX200 droplet dPCR (ddPCR) system (Bio-Rad Laboratories, Inc, Hercules, CA, USA) and the QIAcuity nanoplate-based dPCR (ndPCR) system (QIAGEN Sciences, Inc, Germantown, MD, USA). The primer–probe assay was validated with qPCR, ndPCR and ddPCR using patient samples from pre-clinical CAR T-cell manufacturing production runs as well as Jurkat cell subclones, which stably express this bicistronic CAR construct.ResultsddPCR confirmed the specificity of this assay to detect only the bicistronic CAR product. Additionally, the authors’ assay gave accurate, precise and reproducible CAR T-cell VCN measurements across qPCR, ndPCR and ddPCR modalities.ConclusionsThe authors demonstrate that dPCR strategies can be utilized for absolute quantification of CAR transgenes and VCN measurements, with improved test–retest reliability, and that specific assays can be developed for detection of unique constructs.     

Targeting of low ALK antigen density neuroblastoma using AND logic-gate engineered CAR-T cells

Background aimsThe targeting of solid cancers with chimeric antigen receptor (CAR) T cells faces many technological hurdles, including selection of optimal target antigens. Promising pre-clinical and clinical data of CAR T-cell activity have emerged from targeting surface antigens such as GD2 and B7H3 in childhood cancer neuroblastoma. Anaplastic lymphoma kinase (ALK) is expressed in a majority of neuroblastomas at low antigen density but is largely absent from healthy tissues.MethodsTo explore an alternate target antigen for neuroblastoma CAR T-cell therapy, the authors generated and screened a single-chain variable fragment library targeting ALK extracellular domain to make a panel of new anti-ALK CAR T-cell constructs.ResultsA lead novel CAR T-cell construct was capable of specific cytotoxicity against neuroblastoma cells expressing low levels of ALK, but with only weak cytokine and proliferative T-cell responses. To explore strategies for amplifying ALK CAR T cells, the authors generated a co-CAR approach in which T cells received signal 1 from a first-generation ALK construct and signal 2 from anti-B7H3 or GD2 chimeric co-stimulatory receptors. The co-CAR approach successfully demonstrated the ability to avoid targeting single-antigen-positive targets as a strategy for mitigating on-target off-tumor toxicity.ConclusionsThese data provide further proof of concept for ALK as a neuroblastoma CAR T-cell target.     

Manufacturing chimeric antigen receptor T cells from cryopreserved peripheral blood cells: time for a collect-and-freeze model?

Background aimsChimeric antigen receptor (CAR)-modified T-cell therapy has revolutionized outcomes for patients with relapsed/refractory B-cell malignancies. Despite the exciting results, several clinical and logistical challenges limit its wide applicability. First, the apheresis requirement restricts accessibility to institutions with the resources to collect and process peripheral blood mononuclear cells (PBMCs). Second, even when utilizing an apheresis product, failure to manufacture CAR T cells is a well-established problem in a significant subset. In heavily pre-treated patients, prior chemotherapy may impact T-cell quality and function, limiting the ability to manufacture a potent CAR T-cell product. Isolation and storage of T cells shortly after initial cancer diagnosis or earlier in life while an individual is still healthy are an alternative to using T cells from heavily pre-treated patients. The goal of this study was to determine if a CAR T-cell product could be manufactured from a small volume (50 mL) of healthy donor blood.MethodsCollaborators at Cell Vault collected 50 mL of whole peripheral venous blood from three healthy donors. PBMCs were isolated, cryopreserved and shipped to the Medical College of Wisconsin. PBMCs for each individual donor were thawed, and CAR T cells were manufactured using an 8-day process on the CliniMACS Prodigy device with a CD19 lentiviral vector.ResultsStarting doses of enriched T-cell numbers ranged from 4.0 × 10⁷ cells to 4.8 × 10⁷ cells, with a CD4/CD8 purity of 74–79% and an average CD4:CD8 ratio of 1.4. On the day of harvest, total CD3 cells in the culture expanded to 3.6–4.6 × 10⁹ cells, resulting in a 74- to 115-fold expansion, an average CD4:CD8 ratio of 2.9 and a CD3 frequency of greater than 99%. Resulting CD19 CAR expression varied from 19.2% to 48.1%, with corresponding final CD19+ CAR T-cell counts ranging from 7.82 × 10⁸ cells to 2.21 × 10⁹ cells. The final CAR T-cell products were phenotypically activated and non-exhausted and contained a differentiated population consisting of stem cell-like memory T cells.ConclusionsOverall, these data demonstrate the ability to successfully generate CAR T-cell products in just 8 days using cryopreserved healthy donor PBMCs isolated from only 50 mL of blood. Notably, numbers of CAR T cells were more than adequate for infusion of an 80-kg patient at dose levels used for products currently approved by the Food and Drug Administration. The authors offer proof of principle that cryopreservation of limited volumes of venous blood with an adequate starting T-cell count allows later successful manufacture of CAR T-cell therapy.