Good Manufacturing Practice-compliant human induced pluripotent stem cells: from bench to putative clinical products

BACKGROUND AIMS

Few human induced pluripotent stem cell (hiPSC) lines are Good Manufacturing Practice (GMP)-compliant, limiting the clinical use of hiPSC-derived products. Here, we addressed this by establishing and validating an in-house platform to produce GMP-compliant hiPSCs that would be appropriate for producing both allogeneic and autologous hiPSC-derived products.

METHODS

Our standard research protocol for hiPSCs production was adapted and translated into a GMP-compliant platform. In addition to the generation of GMP-compliant hiPSC, the platform entails the methodology for donor recruitment, consent and screening, donor material procurement, hiPSCs manufacture, in-process control, specific QC test validation, QC testing, product release, hiPSCs storage and stability testing. For platform validation, one test run and three production runs were performed. Highest-quality lines were selected to establish master cell banks (MCBs).

RESULTS

Two MCBs were successfully released under GMP conditions. They demonstrated safety (sterility, negative mycoplasma, endotoxins <5.0 EU/mL and negative adventitious agents), cell identity (>75% of cells expressing markers of undifferentiated state, identical STR profile, normal karyotype in >20 metaphases), purity (negative residual vectors and no plasmid integration in the genome) and potency (expression of at least two of the three markers for each of the three germ layers). In addition, directed differentiation to somitoids (skeletal muscle precursors) and six potential clinical products from all three germ layers was achieved: pancreatic islets (endoderm), kidney organoids and cardiomyocytes (mesoderm), and keratinocytes, GABAergic interneurons and inner-ear organoids (ectoderm).

CONCLUSIONS

We successfully developed and validated a platform for generating GMP-compliant hiPSC lines. The two MCBs released were shown to differentiate into clinical products relevant for our own and other regenerative medicine interests.

Multicenter Experience with Good Manufacturing Practice Production of [11C]PiB for Amyloid Positron Emission Tomography Imaging

Alzheimer's disease (AD) is a neurodegenerative disorder with increasing global prevalence and accounts for over half of all dementia cases. Early diagnosis is paramount for not only the management of the disease, but also for the development of new AD treatments. The current golden standard for diagnosis is performed by positron emission tomography (PET) scans with the tracer [11C]Pittsburg Compound B ([11C]PiB), which targets amyloid beta protein (Aβ) that builds up as plaques in the brain of AD patients. The increasing demand for AD diagnostics is in turn expected to drive an increase in [11C]PiB-PET scans and the setup of new [11C]PiB production lines at PET centers globally. Here, we present the [11C]PiB production setups, experiences, and use from four Danish PET facilities and discuss the challenges and potential pitfalls of [11C]PiB production. We report on the [11C]PiB production performed with the 6-OH-BTA-0 precursor dissolved in either dry acetone or 2-butanone and by using either [11C]CO2 or [11C]CH4 as 11C- precursors on three different commercial synthesis modules: TracerLab FX C Pro, ScanSys, or TracerMaker. It was found that the [11C]CO2 method gives the highest radioactive yield (1.5 to 3.2 GBq vs. 0.8 ± 0.3 GBq), while the highest molar activity (98.0 ± 61.4 GBq/μmol vs. 21.2 to 95.6 GBq/μmol) was achieved using [11C]CH4. [11C]PiB production with [11C]CO2 on a TracerLab FX C Pro offered the most desirable results, with the highest yield of 3.17 ± 1.20 GBq and good molar activity of 95.6 ± 44.2 GBq/μmol. Moreover, all reported methods produced [11C]PiB in quantities suitable for clinical applications, thus providing a foundation for other PET facilities seeking to establish their own [11C]PiB production.

Implementing Ac-225 labelled radiopharmaceuticals: practical considerations and (pre-)clinical perspectives

BACKGROUND

In the past years, there has been a notable increase in interest regarding targeted alpha therapy using Ac-225, driven by the observed promising clinical anti-tumor effects. As the production and technology has advanced, the availability of Ac-225 is expected to increase in the near future, making the treatment available to patients worldwide.

MAIN BODY

Ac-225 can be labelled to different biological vectors, whereby the success of developing a radiopharmaceutical depends heavily on the labelling conditions, purity of the radionuclide source, chelator, and type of quenchers used to avoid radiolysis. Multiple (methodological) challenges need to be overcome when working with Ac-225; as alpha-emission detection is time consuming and highly geometry dependent, a gamma co-emission is used, but has to be in equilibrium with the mother-nuclide. Because of the high impact of alpha emitters in vivo it is highly recommended to cross-calibrate the Ac-225 measurements for used quality control (QC) techniques (radio-TLC, HPLC, HP-Ge detector, and gamma counter). More strict health physics regulations apply, as Ac-225 has a high toxicity, thereby limiting practical handling and quantities used for QC analysis.

CONCLUSION

This overview focuses specifically on the practical and methodological challenges when working with Ac-225 labelled radiopharmaceuticals, and underlines the required infrastructure and (detection) methods for the (pre-)clinical application.

Assessment of Residual Full-Length SV40 Large T Antigen in Clinical-Grade Adeno-Associated Virus Vectors Produced in 293T Cells

Efficient production of adeno-associated virus (AAV) vectors is a significant challenge. Human embryonic kidney HEK293T cells are widely used in good manufacturing practice facilities, producing higher yield of AAV vectors for clinical applications than HEK293 through the addition of a constitutive expression of SV40 large T antigen (SV40T), which stimulates Rep expression. However, the theoretical potential for tumorigenic consequences of a clinical AAV product containing residual DNA encoding SV40T, which may inhibit p53 growth suppressive functions is a safety concern. Although the risk is theoretical, to assure a low risk/high confidence of safety for clinical drug development, we have established a sensitive assay for assessment of functional full-length transcription competent SV40T DNA in HEK293T cell-produced AAV vectors. Using HEK293T generated 8, 9, and rh.10 serotype AAV vectors, the presence of SV40T in purified vector was assessed in vitro using quantitative polymerase chain reaction (qPCR) targeting a 129 bp amplicon combined with nested PCR targeting full-length SV40T DNA. Although low levels of the smaller amplicon were present in each AAV serotype, the full-length SV40T was undetectable. No transcription competent full-length SV40T DNA was observed by reverse transcription-quantitative polymerase chain reaction using an in vivo amplification of signal in mouse liver administered (2-10 × 1010 gc) 129 bp amplicon-positive AAV vectors. As a control for gene transfer, high levels of expressed transgene mRNAs were observed from each serotype AAV vector, yet, SV40T mRNA was undetectable. In vivo assessment of these three liver-tropic AAV serotypes, each with amplicon-positive qPCR SV40T DNA, demonstrated high transgene mRNA expression but no SV40T mRNA, that is, detection of small segments of SV40T DNA in 293T cell produced AAV inappropriately leads to the conclusion of residuals with the potential to express SV40T. This sensitive assay can be used to assess the level, if any, of SV40T antigen contaminating AAV vectors generated by HEK293T cells. ClinicalTrials.gov identifier: NCT03634007; NCT05302271; NCT01414985; NCT01161576.

Upgrading Monocytes Therapy for Critical Limb Ischemia Patient Treatment: Pre-Clinical and GMP-Validation Aspects

Advanced cell therapy medicinal products (ATMP) are at the forefront of a new range of biopharmaceuticals. The use of ATMP has evolved and increased in the last decades, representing a new approach to treating diseases that are not effectively managed with conventional treatments. The standard worldwide recognized for drug production is the Good Manufacturing Practices (GMP), widely used in the pharma production of synthesized drugs but applying also to ATMP. GMP guidelines are worldwide recognized standards to manufacture medicinal products to guarantee high quality, safety, and efficacy. In this report, we describe the pre-clinical and the GMP upgrade of peripheral blood mononuclear cell (PBMC) preparation, starting from peripheral blood and ending up with a GMP-grade clinical product ready to be used in patients with critical limb ischemia (CLI). We also evaluated production in hypoxic conditions to increase PBMC functional activity and angiogenic potential. Furthermore, we extensively analyzed the storage and transport conditions of the final product as required by the regulatory body for ATMPs. Altogether, results suggest that the whole manufacturing process can be performed for clinical application. Peripheral blood collected by a physician should be transported at room temperature, and PBMCs should be isolated in a clean room within 8 h of venipuncture. Frozen cells can be stored in nitrogen vapors and thawed for up to 12 months. PBMCs resuspended in 5% human albumin solution should be stored and transported at 4 °C before injection in patients within 24 h to thawing. Hypoxic conditioning of PBMCs should be implemented for clinical application, as it showed a significant enhancement of PBMC functional activity, in particular with increased adhesion, migration, and oxidative stress resistance. We demonstrated the feasibility and the quality of a GMP-enriched suspension of monocytes as an ATMP, tested in a clean room facility for all aspects related to production in respect of all the GMP criteria that allow its use as an ATMP. We think that these results could ease the way to the clinical application of ATMPs.

Inter-center comparison of good manufacturing practices-compliant stromal vascular fraction and proposal for release acceptance criteria: a review of 364 productions

Background

Even though the manufacturing processes of the stromal vascular fraction for clinical use are performed in compliance with the good manufacturing practices applying to advanced therapy medicinal products, specifications related to stromal vascular fraction quality remain poorly defined. We analyzed stromal vascular fraction clinical batches from two independent good manufacturing practices-compliant manufacturing facilities, the Swiss Stem Cell Foundation (SSCF) and Marseille University Hospitals (AP-HM), with the goal of defining appropriate and harmonized release acceptance criteria.

Methods

This retrospective analysis reviewed the biological characteristics of 364 batches of clinical-grade stromal vascular fraction. Collected data included cell viability, recovery yield, cell subset distribution of stromal vascular fraction, and microbiological quality.

Results

Stromal vascular fraction from SSCF cohort demonstrated a higher viability (89.33% ± 4.30%) and recovery yield (2.54 × 10⁵ ± 1.22 × 10⁵ viable nucleated cells (VNCs) per mL of adipose tissue) than stromal vascular fraction from AP-HM (84.20% ± 5.96% and 2.25 × 10⁵ ± 1.11 × 10⁵ VNCs per mL). AP-HM batches were significantly less contaminated (95.71% of sterile batches versus 74.15% for SSCF batches). The cell subset distribution was significantly different (higher proportion of endothelial cells and lower proportion of leukocytes and pericytes in SSCF cohort).

Conclusions

Both centers agreed that a good manufacturing practices-compliant stromal vascular fraction batch should exert a viability equal or superior to 80%, a minimum recovery yield of 1.50 × 10⁵ VNCs per mL of adipose tissue, a proportion of adipose-derived stromal cells at least equal to 20%, and a proportion of leukocytes under 50%. In addition, a multiparameter gating strategy for stromal vascular fraction analysis is proposed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02445-z.

GMP production of 6-[18F]Fluoro-L-DOPA for PET/CT imaging by different synthetic routes: a three center experience

BACKGROUND

The radiofluorinated levodopa analogue 6-[¹⁸F]F-L-DOPA (3,4-dihydroxy-6-¹⁸F-L-phenylalanine) is a commonly employed radiotracer for PET/CT imaging of multiple oncological and neurological indications. An unusually large number of different radiosyntheses have been published to the point where two different Ph. Eur. monographs exist depending on whether the chemistry relies on electrophilic or nucleophilic radiosubstitution of appropriate chemical precursors. For new PET imaging sites wishing to adopt [¹⁸F]FDOPA into clinical practice, selecting the appropriate production process may be difficult and dependent on the clinical needs of the site.

METHODS

Data from four years of [¹⁸F]FDOPA production at three different clinical sites are collected and compared. These three sites, Aarhus University Hospital (AUH), Odense University Hospital (OUH), and Herlev University Hospital (HUH), produce the radiotracer by different radiosynthetic routes with AUH adopting an electrophilic strategy, while OUH and HUH employ two different nucleophilic approaches. Production failure rates, radiochemical yields, and molar activities are compared across sites and time. Additionally, the clinical use of the radiotracer over the time period considered at the different sites are presented and discussed.

RESULTS

The electrophilic substitution route suffers from being demanding in terms of cyclotron operation and maintenance. This challenge, however, was found to be compensated by a production failure rate significantly below that of both nucleophilic approaches; a result of simpler chemistry. The five-step nucleophilic approach employed at HUH produces superior radiochemical yields compared to the three-step approach adopted at OUH but suffers from the need for more comprehensive synthesis equipment given the multi-step nature of the procedure, including HPLC purification. While the procedure at OUH furnishes the lowest radiochemical yield of the synthetic routes considered, it produces the highest molar activity. This is of importance across the clinical applications of the tracer discussed here, including dopamine synthesis in striatum of subjects with schizophrenia and congenital hyperinsulinism in infants.

CONCLUSION

For most sites either of the two nucleophilic substitution strategies should be favored. However, which of the two will depend on whether a given site wishes to optimize the radiochemical yield or the ease of the use.

Antitumor efficacy of BAFF-R targeting CAR T cells manufactured under clinic-ready conditions

B-cell malignancies can potentially be cured by CD19 chimeric antigen receptor (CAR) T-cell therapy. Although clinical response rates can be up to 93% in acute lymphoblastic leukemia, treatment-related antigen loss and lack of therapeutic persistence contribute to disease relapse. These shortcomings of current CAR T-cell therapy indicate the need for biologically relevant target selection and for improving the efficacy and persistence of the CAR T cells, which we have addressed by developing a novel B-cell activating factor receptor (BAFF-R) CAR T-cell therapy with improved therapeutic persistence. BAFF-R is a B-cell survival receptor and highly expressed in B-cell malignancies. We developed a prototype CAR T cell that efficiently and specifically eliminated BAFF-R expressing human B-cell tumors in several xenogeneic mouse models, including models of CD19 antigen loss. We proceeded with translational development and validation of BAFF-R CAR T cells produced under current good manufacturing practices (cGMP). cGMP-grade BAFF-R CAR T cells underwent in vitro and in vivo validation in established models to confirm that the potency and efficacy of our original research modeling was replicated. Food and Drug Administration required release testing was performed to ensure our BAFF-R CAR T cells meet specifications for new drug products. Completing and exceeding these requirements, the data fully support the initiation of a first-in-human Phase 1 trial for BAFF-R-positive relapsed/refractory (r/r) B-ALL.

Lentivector Iterations and Pre-Clinical Scale-Up/Toxicity Testing: Targeting Mobilized CD34+ Cells for Correction of Fabry Disease

Fabry disease is a rare lysosomal storage disorder (LSD). We designed multiple recombinant lentivirus vectors (LVs) and tested their ability to engineer expression of human α-galactosidase A (α-gal A) in transduced Fabry patient CD34⁺ hematopoietic cells. We further investigated the safety and efficacy of a clinically directed vector, LV/AGA, in both ex vivo cell culture studies and animal models. Fabry mice transplanted with LV/AGA-transduced hematopoietic cells demonstrated α-gal A activity increases and lipid reductions in multiple tissues at 6 months after transplantation. Next we found that LV/AGA-transduced Fabry patient CD34⁺ hematopoietic cells produced even higher levels of α-gal A activity than normal CD34⁺ hematopoietic cells. We successfully transduced Fabry patient CD34⁺ hematopoietic cells with “near-clinical grade” LV/AGA in small-scale cultures and then validated a clinically directed scale-up transduction process in a GMP-compliant cell processing facility. LV-transduced Fabry patient CD34⁺ hematopoietic cells were subsequently infused into NOD/SCID/Fabry (NSF) mice; α-gal A activity corrections and lipid reductions were observed in several tissues 12 weeks after the xenotransplantation. Additional toxicology studies employing NSF mice xenotransplanted with the therapeutic cell product demonstrated minimal untoward effects. These data supported our successful clinical trial application (CTA) to Health Canada and opening of a “first-in-the-world” gene therapy trial for Fabry disease.

Good manufacturing practices production of a purification-free oral cholera vaccine expressed in transgenic rice plants

The first Good Manufacturing Practices production of a purification-free rice-based oral cholera vaccine (MucoRice-CTB) from transgenic plants in a closed cultivation system yielded a product meeting regulatory requirements. Despite our knowledge of their advantages, plant-based vaccines remain unavailable for human use in both developing and industrialized countries. A leading, practical obstacle to their widespread use is producing plant-based vaccines that meet governmental regulatory requirements. Here, we report the first production according to current Good Manufacturing Practices of a rice-based vaccine, the cholera vaccine MucoRice-CTB, at an academic institution. To this end, we established specifications and methods for the master seed bank (MSB) of MucoRice-CTB, which was previously generated as a selection-marker-free line, evaluated its propagation, and given that the stored seeds must be renewed periodically. The production of MucoRice-CTB incorporated a closed hydroponic system for cultivating the transgenic plants, to minimize variations in expression and quality during vaccine manufacture. This type of molecular farming factory can be operated year-round, generating three harvests annually, and is cost- and production-effective. Rice was polished to a ratio of 95 % and then powdered to produce the MucoRice-CTB drug substance, and the identity, potency, and safety of the MucoRice-CTB product met pre-established release requirements. The formulation of MucoRice-CTB made by fine-powdering of drug substance and packaged in an aluminum pouch is being evaluated in a physician-initiated phase I study.

Large-scale manufacturing of GMP-compliant anti-EGFR targeted nanocarriers: production of doxorubicin-loaded anti-EGFR-immunoliposomes for a first-in-man clinical trial

We describe the large-scale, GMP-compliant production process of doxorubicin-loaded and anti-EGFR-coated immunoliposomes (anti-EGFR-ILs-dox) used in a first-in-man, dose escalation clinical trial. 10 batches of this nanoparticle have been produced in clean room facilities. Stability data from the pre-GMP and the GMP batch indicate that the anti-EGFR-ILs-dox nanoparticle was stable for at least 18 months after release. Release criteria included visual inspection, sterility testing, as well as measurements of pH (pH 5.0-7.0), doxorubicin HCl concentration (0.45-0.55 mg/ml), endotoxin concentration (<1.21 IU/ml), leakage (<10%), particle size (Z-average of Caelyx ± 20 nm), and particle uptake (uptake absolute: >0.50 ng doxorubicin/μg protein; uptake relatively to PLD: >5 fold). All batches fulfilled the defined release criteria, indicating a high reproducibility as well as batch-to-batch uniformity of the main physico-chemical features of the nanoparticles in the setting of the large-scale GMP process. In the clinical trial, 29 patients were treated with this nanoparticle between 2007 and 2010. Pharmacokinetic data of anti-EGFR-ILs-dox collected during the clinical study revealed stability of the nanocarrier in vivo. Thus, reliable and GMP-compliant production of anti-EGFR-targeted nanoparticles for clinical application is feasible.