Avecia Biologics" Bo Kara, director of science and technology and Stephen Taylor, director for business development, argue that the biotech sector needs to focus on reducing development time and its technology can help
"Cancer doctors have told the BBC that the NHS (the UK National Health Service) will not be able to afford the new generation of cancer therapeutics" - newswire, May 2007. Such headlines illustrate the expectations and challenges placed on our industry by the patients we seek to serve.
To produce affordable medicines, many other challenges must be met if we are to have an effective, profitable biotech industry. Increasing process productivity and reducing costs are easy to identify as targets for improvement, but equally important is the need to reduce the development time of new treatments. Our industry must become faster at moving projects into the clinic - and better at avoiding repetition because of wrong process choices.
In 10 years as a CMO focused on microbial-derived biologics, Avecia has witnessed examples of how early choices and decisions in a development project's life have profoundly impacted cost and time.
We have also observed the variety of emerging and unique approaches to therapy - but still demand biological manufacture. Antibody fragments and chemical modification of proteins, nucleic acid-based treatments and gene therapy, cell-based treatments and stem cell approaches, the list constantly grows. Many show real promise in the clinic - but will they translate into affordable, profitable medicines?
How should the industry deal with the apparent conflicts of creating more value, more profitable and timely new drugs while improving affordability restricted by tightening healthcare budgets and dealing with the uniqueness of each new product?
The 2006 BioPlan survey1 stated: "Many of the most challenging process development and manufacturing projects are the ones outsourced to CMOs."
This reflects the growing complexity of process development and that the core competences needed are not part of the average biotechnology company's armoury. Indeed the pace of development and the regulatory process' changing requirements suggest we should start to consider "c-process development' as a direct analogy to the need for keeping current in GMP thinking.
Thus, Avecia Biologics and other such companies must lead the charge to ensure that process science and technology will meet the challenges of the next biologics generation.
Nowhere is the drive to achieve increased production titres more evident than in the monoclonal antibody field. As was evident at BIO2007 in Boston, major and minor players are introducing systems delivering grams per litre of product with some companies claiming to achieve 10g per litre. Antibodies have the advantage that the purification strategies required are largely conserved from one product to the next. But, does the same philosophy apply to biologics that fall outside the monoclonal antibody family?
Outside monoclonal antibodies, the products themselves have huge variety - enzymes, cytokines, interferons, growth factors, vaccines, various formats of fusion proteins and more. The target therapies and hence product characteristics vary enormously leading to diverse purity, cost-of-goods and volume requirements. In this market sector, microbial, rather than cell culture, manufacturing is introducing a different set of processing paradigms.
Therefore, the processing strategies for products tend to be customised both upstream and downstream, and a wide range of process options have to be available when commencing a development programme covering expression vectors, host strains, fermentation conditions, whether the product will be accumulated intracellularly as inclusion bodies or in a soluble form or secreted (periplasmic or extracellular) and the different downstream approaches that follow.
Avecia's experience with the many different microbial-biologics enables the company to take on an holistic approach to process development. Away from monoclonal antibodies, this variability in products and the need for customised solutions becomes increasingly clear.
Striving for high grams per litre is of course vital - but it's not the full story. There are two specific consequences:
1. The relatively long time typically taken to establish a process suitable for manufacture of toxicology and phase 1 clinical material: time is value
2. The major risk of a process at the start of development to deliver the performance required later in development to underpin validation, approval and market acceptance: major process re-development is time and value.
The industry often focuses too much on 'stainless steel' or the manufacturing assets, giving insufficient attention to the real benefits and needs that sit with the process science. Even concentrating on the science, we can become obsessed with grams per litre and overlook key features that will ultimately govern manufacturing performance. There are many different avenues in a development programme and it is important to select the one best favouring the target product and its application rather than simply using 'flavour of the month' technology.
We have also observed that making choices early in development that enable 'validatability' and 'scalability' to be built into a process at the start, avoiding issues that can emerge late in development when the need arises to demonstrate process understanding, robustness and control. These requirements are time- and cash-consuming and regulators worldwide are focusing more on the quality and comprehensiveness of the work - the concept of Quality by Design.
Therefore, Avecia's core process philosophy is that the choice of expression vector, host organism, strain construction, fermentation and purification strategies must be viewed, and addressed, in an integrated approach and aligned with the product's characteristics.
With this in mind the company set out to exploit its patented science in gene expression with real practical experience of fermentation and purification development programmes to provide customers with an approach to the earliest stages of process development, the actual creation of the basic process - that delivered them real and tangible benefits. It sought to:
- minimise the time needed to establish a development-suitable process, starting from a gene sequence;
- enable a fast comparison of process options;
- establish early the basis for a high-productivity process ;
- provide a dependable basis for future scale-up and validation;
- offer versatility to meet the demands of very different products;
- use well characterised systems to underpin regulatory confidence.
The first result is pAVEway - a new platform based on protein expression plasmids, developed by Avecia. Using a novel configuration of operators, promoters and repressors, the company has created a range of vectors that provide tightly controlled production of the target proteins while allowing very high expression levels.
However, the fact that these vectors are complemented by a range of selected and proven host strains with well developed and characterised high titre fermentation strategies, also makes a difference. By choosing the appropriate combination of plasmid, host strain and fermentation conditions, very high titres have been demonstrated for soluble, insoluble and secreted proteins with a sound and proven basis for development and scale-up.
No single system or approach will meet all demands. A development programme has to consider most major options before focusing down and pAVEway allows that scope to be narrowed.
E. coli is the undisputed proven workhorse of our industry, well accepted by the regulators and capable of delivering high productivity processes. However, it is worth bearing in mind that not all E. coli host strains are the same! Selectivity here is also an essential pre-requisite to successful development. We have defined five core E. coli systems that cover all main eventualities from inclusion body production to soluble and secreted proteins coupled with the range of product types from relatively simple mono-meric proteins to complex multi-meric ones.
Starting with the gene of interest, the process flow is expressing the protein in a pre-defined set of pAVEway vectors, cloning these in a range of corresponding host strains and growing them in a selection of pre-established generic optimal conditions. This process, lasting a maximum of four weeks, enables rapid selection of an optimal expression system and early definition of the upstream production process, allowing key manufacturing platform decisions to be made quickly using a robust data set.
Examples are shown in Table 1 where seven very different proteins have been used as models to illustrate the impact. The titres shown were achieved in the first evaluation of recombinants using the pre-established pAVEway fermentation protocol and within four weeks of starting. No one should pretend that this is the end of the development story. To support an approved biologic, a long development activity path is inevitable to ensure a safe, effective and robust manufacturing process - but it does give a strong platform on which to build a process development programme paralleling the product development. Furthermore, it significantly reduces the time needed to make those essential first steps into the clinic with a process that genuinely offers the foundation on which to build.
Using pAVEway, very high fermentation yields have been achieved for a range of proteins, as above. In achieving this, the platform combines two critical features.
Firstly, many if not most pre-existing systems fall down because of 'leakiness'. When stressed under production conditions, the basal expression level isn't zero, which can impact the overall performance particularly in situations where the product doesn't have a neutral impact on the host organism. With pAVEway, the basal expression level can be fully suppressed (Table 2) so that no target protein is produced before induction or after prolonged incubation in the absence of inducer addition. This allows for high cell density and high expression even for proteins that would normally impair the growth of the host.
The second characteristic is the ability to modulate expression levels, in a near linear manner, by varying the concentration of inducer (Figure 1). Maximum expression rate is not always the best solution! The expression kinetics can thus be tightly regulated to match the protein synthetic capacity or the protein-folding capabilities of the host cell, enabling, for example, the soluble expression of proteins of high folding complexity.
The application of pAVEway to many different proteins has been indicated above and this is a vital feature for any microbial platform. The impact of this in E. coli is illustrated below, showing the benefits and outcomes.
But while E. coli is undoubtedly the first choice, there are clearly occasions when alternative hosts can bring additional benefits. With very complex products, yeasts such as Pichia can bring tangible benefit and with products now late in development it will not be long before the regulatory track record starts to build impressively.
Other bacteria such as pseudomonas may also have utility and some evidence suggests proteins expressing as inclusion bodies in E. coli can be made more effectively in soluble pseudomonas. This area needs further study and better like-for-like comparisons, but we have shown that pAVEway is equally applicable in this host. Data achieved with both enzymes and growth factors has shown delivery of yields in excess of 10 grams per litre of active protein.
Fast into the clinic with a sound foundation on which to build are key benefits of pAVEway. But the CMO sector must use its collective knowledge as more biotechnology companies derive benefits from outsourcing, and use this to tailor and steer the development of new science and technology that meets our customers' real issues.
Technology is already transforming the antibody sector where the yields now being achieved are light years from five years ago when the facility 'building boom' took off. We can now observe how antibody capacity is likely to be in excess in future years, due to the impact of this science. pAVEway is one example of how development in the microbial sector is also helping to meet a similar stakeholder demand but with a wider type and class or product molecules.
In recognising the importance of new science and technology we would like to take this opportunity to blow the trumpet for the UK. In 2003, a far-sighted government report identified bio-processing as a key area underpinning the growth of the UK, and recognised it as the best place for biotechnology drug development. This resulted in 'bioProcessUK', a pan-industry organisation leading the drive to bring biotechnology, pharmaceutical, CMO companies together with academia and push through a programme of innovative and strategic bio-processing science. The first phase of a multi million-pound research programme is now established with research council and industry funding.
In conclusion we have indicated that new science and technology will improve the value of our industry, creating more effective and profitable new treatments - and ultimately contributing towards improving affordability. pAVEway is an example of Transforming Technology from Avecia that addresses the key aspects of speed into early development, high productivity and creating a sound basis for future scale-up.