The rapidly growing interest for cell and gene therapies demands the development of robust, scalable, and cost-effective bioprocesses for viral vector production. For the production of lentiviral vector (LVV) at high titers, we have developed an inducible packaging system in suspension HEK293 cells from which we can also generate stable producer cell lines, in serum-free conditions. To evaluate the potential of this platform, we have generated a stable cell line that produces an LVV encoding a green fluorescent protein (GFP) and obtains 10E+07 to 10E+08 transduction units (TU)/mL at the 4 L, 10 L and 50 L scales. Functional LVV titers were maintained across all scales in bioreactors with different configurations and geometries indicating process robustness. Further, the addition of 10% feed increased the volumetric productivity by 3.5-fold in comparison to batch production, making our platform suitable for large-scale LVV production and showing a real potential for commercial manufacturing.
Category: <span>Viral Vectors</span>
The heterogenous group of advanced therapy medicinal products (ATMPs) are biologics with frequently limited viral safety profiles. As compared to well-established biologics such as monoclonal antibody products, the risk of virus contamination is significantly higher for some ATMPs. The standard approaches and tools used to mitigate the viral risk have limitations, leaving open the chances of missing virus contamination in an ATMP manufacturing process in both upstream and downstream. Next-generation sequencing (NGS) technology can overcome the residual risk by having the potential to detect any kind of virus contamination based on its inherent capability to detect any kind of nucleic acid in a sample. It perfectly combines the benefits and compensates for the downsides of the existing testing tools. It will replace a bunch of different established testing methods at improved turnaround times and, in the end, reduced overall costs. The combination of these characteristics is making NGS-based virus testing an in-demand and preferred approach to mitigating the virus contamination risk across all kinds of biologics mid- and long-term.
To demonstrate that a dose-determining assay is fit for purpose, the measurement uncertainty associated with a reported release test result must be suitably small. The establishment of a corresponding product specification is inextricably linked to the tolerance for error in assigning a dose value for a vector lot. By adopting an equivalence-based lot release model which includes a total error approach to assay qualification, specific testing strategies can be evaluated quantitatively for dose error and lot release decision risks throughout the drug development process. This article aims to reinforce how the concepts tied to an equivalence-based lot release model are interrelated and applied in practice. It provides in-depth explanations of fundamental concepts and clarifies common misunderstandings for quality control, quality assurance, and regulatory affairs personnel held accountable for decisions made in vector dose assignment and product lot release.
The approval of several gene therapy products and gene-modified cell therapies over the last five years has led to increasing numbers of investigational new drug applications (INDs) using adeno-associated and lentiviral vectors. However, these successes have been tempered by the risks of dose-related toxicities. The therapeutic window for a product is derived from pre-clinical and clinical dose response models, which assume statistically that measurements of dose are exact. Whether vector is administered directly or used as a critical reagent to prepare a gene-modified cellular product, the assignment of a label concentration to a vector batch is critical for establishing consistency of product used in preclinical and clinical development.
NOTE: Page 7 of this article has been revised to correct an error in the original article which stated that “..the probability of failing a lot when it actually is not equivalent, becomes 1-2*α.” The correct equation, 1-α, has replaced the errant one and a single sentence following it was added to further clarify this concept.
ABSTRACT: Pre-clinical and clinical trials conducted to establish the minimum effective dose and the maximum tolerated dose of a viral vector assume that the assigned dose values are comparable across studies. Toxicity has been associated with high dose administration of both adenovirus and adeno-associated virus-based vectors, and increased attention must be paid to assays used to measure dose. High assay variability can be mitigated by replication and the reporting of a mean value for product lot release. The establishment of a dose specification and a testing strategy must take into account the risk of errant quality control decisions. This can be accomplished by linking assay qualification information to measurement uncertainty through a statistical framework. By adopting an equivalence approach, the risk of releasing lots with unacceptably high or low dose values is minimized by reducing measurement uncertainty. This article provides a worked-through example to introduce applicable statistical concepts and the equations necessary to facilitate their implementation in the field.
Fujifilm Diosynth Biotechnologies (FDB) is a global contract development and manufacturing organization (CDMO) with over 25 years of experience in process development and/or manufacturing of greater than 310 molecules at sites in: Billingham, England; Research Triangle Park, North Carolina; and College Station, Texas. At our College Station location, we specialize in the development and manufacture of virus-based vaccines (attenuated or recombinant viruses), oncolytic viral therapies (such as adenovirus, polio) and gene therapy vectors (such as adeno-associated virus [AAV])…
Cell substrates are used in various stages of viral vaccine manufacturing, as in the isolation, selection, and propagation of the virus seed or virus vector stock, as well as for the amplification of the virus to produce the final vaccine product. The various stages of cell substrate use, including cell banking, are shown in a generic manufacturing scheme in Figure 1. Traditionally, viral vaccines have been produced in animal tissues, primary cell cultures, and cell lines that either have a finite life span, such as normal diploid cells, or a theoretically infinite life span, as achieved with continuous or immortalized neoplastic cells. The cell substrates used in viral vaccines currently licensed in the US are listed in Table 1…
Recombinant adeno-associated viral (rAAV) vectors have proven to be efficient vehicles for gene transfer in animal models. The attractive features of this vector system are long-term gene expression with little or no associated toxicities following administration to a variety of tissues. Previous and ongoing clinical trials in humans demonstrate a very good over-all safety profile. However, one of the caveats of this work that has been carried out by several laboratories is the inability to normalize vector doses administered by different investigators to animals and humans. Most of the work to date has involved AAV serotype2 vectors, but vector systems based on other AAV serotypes are being rapidly developed…
Biopharmaceutical companies are constantly evaluating new methods for mammalian cell line development that provide benefits such as shorter timelines, improved consistency, higher production, better genetic stability, and increased flexibility. Each of these advantages extends a large cost benefit to companies as their recombinant protein products are moved from development into the clinic and finally to commercial launch. A versatile system has been developed that is capable of transferring genes of interest into a wide variety of mammalian host cells and offers a number of the above advantages over other methods. The system, which is referred to as GPEx™ (an acronym for “gene product expression”), utilizes replication-defective retroviral vectors, derived from Moloney murine leukemia virus (MLV) and pseudotyped with vesicular stomatitis virus G protein (VSV-G), to stably insert single copies of genes into dividing cells…
Vaccines represent the most effective means of disease prevention. A variety of vaccines including live-attenuated strains, inactivated organisms, and subunit forms are currently in use. However, advances in molecular biology, virology and immunology have made new classes of potential vaccines possible. One such class currently being developed by AlphaVax is based on an alphavirus-derived expression system. Alphaviruses are members of the Togaviridae family and have positive-sense RNA genomes. The RNA genome is surrounded by a capsid composed of 240 copies of a single capsid protein. Alphaviruses are enveloped viruses that mature at the plasma membrane of the host cell and are 50-70 nm in diameter. The viral envelope contains 80 trimers composed of two viral glycoproteins, E1 and E2. These trimers contain three E1-E2 heterodimers and are arranged in the viral envelope as spikes which protrude from the surface of the virus particle…