Biopharmaceuticals scale

Four column systems are available from Amersham Pharmacia Biotech that can be used to pack SEC media for various applications at the laboratory scale. These include C, XK, SR, and HR column systems. All of the laboratory-scale columns are constructed with borosilicate glass tubes. Columns for larger scale process applications include INdEX, BPG, EineLINE, BPSS, and Stack columns. The larger scale columns are constructed to meet stringent validation requirements for the production of biopharmaceuticals. Each of the column types are described. 

The advantages of such biotransformation processes are (1) the relatively high yields which can be achieved with specific enzymes, (2) the formation of chiral compounds suitable for biopharmaceuticals, and (3) the relatively mild reaction conditions. Key issues in industrial-scale process development are achieving high product concentrations, yields and productivities by maintaining enzyme activity and stability under reaction conditions while reducing enzyme production costs. 

The principal considerations involved in design of a process-scale chromatographic purification include scalability, reproducibility, safety, and validatability. Cost factors, however, must by necessity enter into all industrial decisions. Due to the high value-added nature of most biopharmaceuticals, this cost factor is driven by throughput, rather than by capital investment cost. 

Avecia is a biotechnology company directed to the development and manufacturing of biotechnology based medicines. It is structurally organized in two business units, namely Biologies and DNA Medicines. Its capabilities comprise process development, scale-up, and manufacture of microbial-derived biopharmaceuticals and oligonucleotides. 

In this review, we focus on the use of plant tissue culture to produce foreign proteins that have direct commercial or medical applications. The development of large-scale plant tissue culture systems for the production of biopharmaceutical proteins requires efficient, high-level expression of stable, biologically active products. To minimize the cost of protein recovery and purification, it is preferable that the expression system releases the product in a form that can be harvested from the culture medium. In addition, the relevant bioprocessing issues associated with bioreactor culture of plant cells and tissues must be addressed. 

The physicochemical and other properties of any newly identified drug must be extensively characterized prior to its entry into clinical trials. As the vast bulk of biopharmaceuticals are proteins, a summary overview of the approach taken to initial characterization of these biomolecules is presented. A prerequisite to such characterization is initial purification of the protein. Purification to homogeneity usually requires a combination of three or more high-resolution chromatographic steps (Chapter 6). The purification protocol is designed carefully, as it usually forms the basis of subsequent pilot- and process-scale purification systems. The purified product is then subjected to a battery of tests that aim to characterize it fully. Moreover, once these characteristics have been defined, they form the basis of many of the QC identity tests routinely performed on the product during its subsequent commercial manufacture. As these identity tests are discussed in detail in Chapter 7, only an abbreviated overview is presented here, in the form of Figure 4.5. 

Figure 4.9 Scale-up of proposed biopharmaceutical production process to generate clinical trial material, and eventually commercial product. No substantive changes should be introduced to the production protocol during scale-up...

The upstream processing element of the manufacture of a batch of biopharmaceutical product begins with the removal of a single ampoule of the working cell bank. This vial is used to inoculate a small volume of sterile media, with subsequent incubation under appropriate conditions. This describes the growth of laboratory-scale starter cultures of the producer cell line. This starter culture is, in turn, used to inoculate a production-scale starter culture that is used to inoculate the production-scale bioreactor (Figure 5.7). The media composition and fermentation conditions required to... 

Figure 5.8 Typical industrial-scale fermentation equipment as employed in the biopharmaceutical sector (a). Control of the fermentation process is highly automated, with all fermentation parameters being adjusted by computer (b). Photographs (a) and (b) courtesy of SmithKline Beecham Biological Services, s.a., Belgium. Photograph (c) illustrates the inoculation of a laboratory-scale fermenter with recombinant microorganisms used in the production of a commercial interferon preparation. Photograph (c) courtesy of Pall Life Sciences, Dublin, Ireland...

Over half of all biopharmaceuticals thus far approved are produced in recombinant E. coli or S. cerevisiae. Industrial-scale bacterial and yeast fermentation systems share many common features, an overview of which is provided below. Most remaining biopharmaceuticals are produced using animal cell culture, mainly by recombinant BHK or CHO cells (or hybridoma cells in... 

Fermentation follows for several days subsequent to inoculation with the production-scale starter culture (Figure 5.7). During this process, biomass (i.e. cell mass) accumulates. In most cases, product accumulates intracellularly and cells are harvested when maximum biomass yields are achieved. This feed batch approach is the one normally taken during biopharmaceutical manufacture, although reactors can also be operated on a continuous basis, where fresh nutrient media is continually added and a fraction of the media/biomass continually removed and processed. During... 

Overall, therefore, the routine manufacture of a biopharmaceutical product is initiated by large-scale culture of its producing cell line (upstream processing). Subsequent to this, the product is recovered, purified and formulated into final product format. These latter operations are collectively termed downstream processing and are described in Chapter 6. 

The first step in biopharmaceutical development is the selection of a clone in a specific cell line. Whole-mass analysis, if possible, is a fairly simple and powerful tool at this stage to verify the successful expression and translation of the desired protein. VanAdrichem et al.65 described the use of MALDI MS to monitor protein expression in several mammalian cell lines like CHO DXB11, CHO SSF3, and hybridomas. Quantitative MALDI-TOF MS measurements of an IgG antibody and insulin during large-scale production in hybridoma cells were comparable to affinity chromatography results. 

The ELISA is a versatile method that can be used throughout the biopharmaceutical product development process, from small-scale research to cell-line selection, to monitoring fermentation and downstream processing, and to product release testing. The use of the microtiter plates allows for high sample throughput and various degrees of automation. ELISAs satisfy the biopharmaceutical production requirements for specific, accurate, precise, and reproducible assays. 

Overall, the development of a robust formulation with scale-up potential for Phase II studies involves integration of physicochemical, biopharmaceutical, and technical considerations. Whether a rudimentary formulated capsule or a more robust formulation closer to the commercial form will be used in Phase II studies will depend on the company policy, material cost, the complexity of clinical design, and the development strategy. 

In the last two decades, CE has advanced significantly as a technique for biomolecular characterization. It has not only passed the transition from a laboratory curiosity to a mature instrument-based method for micro-scale separation, but has also emerged as an indispensable tool in the biotech and pharmaceutical industries (Chapter 14). CE has become a method of choice in R D for molecular characterization, and in QC for release of therapeutic biomolecules. In the biopharmaceutical industry, more and more CE methods have been validated to meet ICH requirements. To demonstrate the influence of CE in RScD for method development and in manufacturing for the release of therapeutic proteins and antibodies, examples from the pharmaceutical industry are provided in Chapter 14. 

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