Anne Bondgaard Tolstrup

Consistent manufacturing and quality control of a highly complex recombinant polyclonal antibody product for human therapeutic use.

The beneficial effect of antibody therapy in human disease has become well established mainly for the treatment of cancer and immunological disorders. The inherent monospecificity of mAbs present limitations to mAb therapy which have become apparent notably in addressing complex entities like infectious agents or heterogenic endogenous targets. For such indications mixtures of antibodies comprising a combination of specificities would convey more potent biological effect which could translate into therapeutic efficacy. Recombinant polyclonal antibodies (rpAb) consisting of a defined number of well‐characterized mAbs constitute a new class of target specific antibody therapy. We have developed a cost‐efficient cell banking and single‐batch manufacturing concept for the production of such products and demonstrate that a complex pAb composition, rozrolimupab, comprising 25 individual antibodies can be manufactured in a highly consistent manner in a scaled‐up manufacturing process. We present a strategy for the release and characterization of antibody mixtures which constitute a complete series of chemistry, manufacturing, and control (CMC) analytical methods to address identity, purity, quantity, potency, and general characteristics. Finally we document selected quality attributes of rozrolimupab based on a battery of assays at the genetic‐, protein‐, and functional level and demonstrate that the manufactured rozrolimupab batches are highly pure and very uniform in their composition. Biotechnol. Bioeng. 2011;108:2171–2181.

Recombinant antibody mixtures: production strategies and cost considerations.

Recombinant monoclonal antibodies have during the last two decades emerged as a very successful class of biological drugs for the treatment of a variety of different diseases used either as biological mono therapy or in combination with small molecule based drugs. Recombinant antibody mixtures offering targeting of more than one antigen is one of the new promising antibody technologies resulting in higher therapeutic effectiveness and/or broader reactivity. Such recombinant antibody mixtures can in principle be manufactured by different approaches but two main strategies is often applied, either individual manufacturing of the constituent antibodies or single batch manufacturing of the recombinant antibody mixture. Symphogen has developed an expression platform, Sympress™, allowing single batch manufacturing of recombinant antibody mixtures, while other companies are currently using a manufacturing strategy based on production of the individual constituent monoclonal antibodies. An overview and comparison of the different approaches with focus on the challenges in terms of cell banking strategy, manufacturing approach, and strategies for release and characterization will be reviewed in the present manuscript. Furthermore, the two manufacturing approaches are compared based on different parameters such as development timelines, preclinical developmental costs, and manufacturing cost of goods sold (COGS). We conclude that the single batch manufacturing approach expressing a mixture of full length IgG provides a robust and reproducible platform that can be used for cost effective manufacturing of recombinant antibody mixtures.

Manufacture of recombinant polyclonal antibodies

Polyclonal antibody therapy in the form of hyper-immune serum has for more than a century been used for treatment of many infectious diseases. However, with the emergence of first antibiotics and later recombinant monoclonal antibody therapy, the use of hyper-immune serum has declined. The main reason for this is that methods for consistent manufacturing of safe hyper immune immunoglobulin products have been lacking. In contrast, manufacturing processes of recombinant monoclonal antibodies follow a well established schedule and it appears obvious to use similar methods to produce recombinant polyclonal products. However, the methods for monoclonal antibody manufacturing are, for several reasons, not directly applicable to generation and manufacture of polyclonal recombinant antibodies. A new production strategy based on recombinant mammalian producer cells has recently been developed to support consistent generation of recombinant polyclonal antibodies for therapeutic use. This review describes aspects of this novel technology with emphasis on the generation, production and characterization procedures employed, and provides comparison with alternative polyclonal and monoclonal antibody manufacturing strategies.

Single-Batch Production of Recombinant Human Polyclonal Antibodies

We have previously described the development and implementation of a strategy for production of recombinant polyclonal antibodies (rpAb) in single batches employing CHO cells generated by site-specific integration, the SympressTM I technology. The SympressTM I technology is implemented at industrial scale, supporting a phase II clinical development program. Production of recombinant proteins by site-specific integration, which is based on incorporation of a single copy of the gene of interest, makes the SympressTM I technology best suited to support niche indications. To improve titers while maintaining a cost-efficient, highly reproducible single-batch manufacturing mode, we have evaluated a number of different approaches. The most successful results were obtained using random integration in a new producer cell termed ECHO, a CHO DG44 cell derivative engineered for improved productivity at Symphogen. This new expression process is termed the SympressTM II technology. Here we describe proof-of-principle data demonstrating the feasibility of the SympressTM II technology for single-batch rpAb manufacturing using two model systems each composed of six target-specific antibodies. The compositional stability and the batch-to-batch reproducibility of rpAb produced by the ECHO cells were at least as good as observed previously using site-specific integration technology. Furthermore, the new process had a significant titer increase.

Development of recombinant human polyclonal antibodies for the treatment of complex human diseases

Antibodies are a central factor in the immunity against invading pathogens, such as bacteria and viruses, as well as against malignantly transformed cells. Natural antibody responses are polyclonal, comprising antibodies against several epitopes, thus increasing the probability of eliminating the invading pathogen or malignant cell. The pharmacological advantage of polyclonality is exploited in the plasma-derived immunoglobulin products used at present to treat a number of infectious diseases. However, the use of plasma-derived products is limited by their cost, inconvenience of use and potential for transferring diseases from the donor to the patient. Symphogen has developed technologies to capture the advantages of antibody polyclonality while eliminating the potential safety risk associated with the sourcing of human material. Hence, the Symplex™ technology has been developed to identify diverse repertoires of target-specific, fully human antibodies. For the controlled manufacture of recombinant polyclonal antibody drugs, Symphogen has developed the Sympress™ technology. Combined, these two technologies allow the identification and industrial manufacturing of recombinant human polyclonal antibodies for medical use in humans. The authors believe that this new class of therapeutic antibodies will be advantageous in the treatment of complex human diseases, such as cancer and infection, as it allows the combination of several treatment modalities in one drug.

Efficient Expression from One CMV Enhancer Controlling Two Core Promoters

The human CMV promoter/enhancer is one of the strongest promoters for recombinant protein expression in mammalian cells, making the promoter very popular for production of recombinant antibodies. We used an antibody vector design where the antibody heavy and light chain genes were transcribed from a promoter complex consisting of two promoters arranged divergently with the 5′ ends of the promoters in close proximity. However, when two identical CMV promoters constituted this promoter complex, the antibody expression observed was lower than expected based on the strength of the individual promoters. To optimize expression we prepared truncated promoter complexes where only one CMV enhancer controlled the initiation of transcription from two divergent minimal CMV core promoters. Antibody expression from the truncated promoter complexes was analyzed both when transiently transfected and upon stable site-specific integration into a CHO DG44 derived cell line. The data showed that it was possible for one enhancer to drive the expression of two core promoters. However, efficient expression from both divergent core promoters was seen only when the unique region upstream of the CMV enhancer was removed. Notably, a 12-fold increase in expression was found from the best of the truncated promoter complexes after stable site-specific integration when compared to the full-length double CMV promoter complex.

Recombinant antibody mixtures; optimization of cell line generation and single-batch manufacturing processes

Background Recombinant antibody mixtures represent an important new class of antibody therapeutics as demonstrated by the increasing amount of literature showing that combinations of two or more antibodies show superiority compared to monoclonal antibodies (mAbs) for treatment of cancer and infectious diseases [1-5]. Sym004, composed of two antibodies targeting non-overlapping epitopes of the epidermal growth factor receptor (EGFR) act in a synergistic manner to induce an efficient internalization of EGFR leading to subsequent degradation and exhibit superior anticancer efficacy as demonstrated in several preclinical in vivo models [5]. At Symphogen A/S, we have developed an expression platform, SympressTM, for cost-efficient production of antibody mixtures. The antibody mixtures are produced using a single-batch manufacturing approach where a polyclonal working cell bank (pWCB) prepared by mixing the individual stable cell lines producing all the desired antibodies is used as seed material for a bioreactor process [6]. By using a single-batch approach the CMC development costs of antibody mixtures are comparable to costs for monoclonal antibodies. However, the single-batch manufacturing approach raises questions with regard to control of composition ratios, compositional stability and robustness of the cell banking procedure. Here, we present experimental data addressing these key questions and demonstrate that mixtures of recombinant antibodies can be produced under predictable, reproducible and stable conditions using the SympressTM technology.