Xcyte Therapies has recently introduced a bioreactor-based process for the GMP manufacture of autologous activated T cells, Xcellerated T Cells™, for clinical trials. Using a single customized disposable 20-L Cellbag™ with a working volume of 10 L on a customized Wave Bioreactor platform (Wave Biotech, Bridgewater, NJ), the Xcellerate™ III Process has supplanted the 60-L static Xcellerate II Process that used 60 bags cultured in a standard incubator. Compared to the Xcellerate II™ Process, the Xcellerate III Process significantly reduces the overall labor, the number of culture containers, bag spikes, and sterile connections required, as well as reducing the process volume and the cost of goods, while more than quadrupling the final cell density and doubling the facility capacity. These process improvements are achieved without compromising final product composition or quality…
BioProcessing Journal Posts
Cation exchange chromatography (CEX) is a versatile method for separation of proteins based on exploiting differences in positive electrostatic charges. In CEX, proteins are bound to the negatively charged stationary phase (cation exchangers) and then eluted using a salt gradient. Typically, the liquid-phase pH in CEX is lower than the isoelectric points (pI) of the proteins. CEX has been used to monitor various post-translational modifications such as glycosylation, deamidation, phosphorylation, truncation, oxidation, C-terminal and N-terminal clipping, and N-terminal cyclization. Some of these variants may exhibit different bioactivity. Therefore, it is important to characterize protein variants and monitor the stability of these variants throughout the process of drug discovery, development, and manufacture. Characterization of complex proteins such as antibodies, has traditionally been performed using slab gel-based techniques such as isoelectric focusing (IEF). This technique is qualitative and time consuming. It also generates large quantities of chemical waste from the staining process…
Over the past decade there has been a steady increase in the number of biotherapeutics requiring high doses and long term administration. Most notable among these are monoclonal antibodies (MAbs) and fusion proteins comprised partially of antibody molecules. Column chromatography is a commonly applied purification method for downstream processing of biotherapeutics, and there is considerable pressure to process much greater volumes at a faster rate. For recombinant proteins and MAbs, a variety of chromatographic methods are employed, including affinity, ion exchange, hydrophobic interaction, and to a lesser extent, immobilized metal affinity and gel filtration. Improving process control for chromatography operations is essential for biopharmaceutical manufacturers to process larger volumes and overcome capacity shortfalls. As the past ten years have seen increasing volumes of MAb-based drugs, there have been significant innovations to address growing productivity requirements. Dominant among these has been high throughput media capable of isolating product at faster rates than previously achievable…
The safety of our food supply is a major public health concern for consumers, government regulatory agencies, and the food industry. Earlier generations may recall when fresh produce was largely domestic and seasonal. Today we live in a global marketplace, where fresh fruits and vegetables may be on the vine overseas one day and on our grocer’s shelf the next. Although this has provided more yearround variety of foods for the consumer, a lack of uniformity in established agricultural standards and practices among international trading partners (e.g., sanitary issues and inspections) may ultimately lead to deleterious health effects. This is evident in the number of food-borne illness outbreaks and associated deaths. Negative economic consequences also result through lost wages and productivity, and health care costs. The impact can be far greater in developing nations. Therefore, refining domestic and international food safety policies is at the forefront of many government agencies’ efforts toward protecting the public health. Reducing the number of such incidences has become a priority for government regulatory agencies and the food industry…
Monoclonal antibodies (MAbs) destined for use in drug-specific assays must meet specific binding criteria, and therefore require much more in the way of development than many protein-specific antibodies. This article describes one way to facilitate the development of well-characterized, high specificity MAbs. Essentially the same techniques have also been used for producing MAbs that are cancer markers and MAbs that are specific for infectious agents. Monoclonal antibody development, as in other endeavors, requires clearly defined goals and an examination of proposed methods to attain them. This has been succinctly stated by the phrase “Start with the end in mind.” Unfortunately, the vast majority of hybridoma development could be more appropriately described by Yogi Berra, “If you don’t know where you are going, you will wind up somewhere else.” In most laboratories, fusions are carried out with the goal of reducing the amount of cell culture and handling required and using the minimum amount of screening. Little or no consideration is given to ensuring that single clones are subjected to the screening tests. Under these conditions, it is little wonder that dozens of fusions can be carried out, each with the same result — no specific antibody found…
G protein-coupled receptors (GPCRs) comprise a “superfamily” of cell surface receptors that play a prominent role in cell signalling and are classified into more than 100 subfamilies according to sequence, ligand structure, and receptor function. They are cell surface receptor proteins with seven transmembrane domains which transduce extracellular signals to the interior of cells through heterotrimeric G proteins. GPCRs’ exposure at the exterior cell surface and strong role in cell regulation has provided a rich target family for small compound therapeutics. Of the estimated 35,000 genes in the human genome, approximately 750 encode for GPCRs; half likely encoding sensory receptors, the remaining half representing potential drug targets. Only about 30 of these potential targets are currently modulated by existing pharmaceuticals with approximately 400 remaining potential pharmaceutical targets for validation…
lation components that stabilize the molecule in order to provide the desired product storage stability. Generally, an aqueous formulation is preferred; however, the instability of proteins, both physical (e.g. aggregation) and chemical (e.g. deamidation and oxidation), often necessitates the development of lyophilized formulations. In these formulations, selection of the appropriate stabilizing cryoprotectants, lyoprotectants, and bulking agents is critical. Accelerated stability studies are typically used to evaluate the effect of a single factor at a time in order to identify the optimum pH, buffer, and stabilizing excipients. This approach is limited in that many independent time-consuming experiments must be run, the results are obtained only at the evaluated set points, and additional experiments are required to assess potential interactions between the evaluated factors…