Priyabrata Pattnaik, director, Worldwide Vaccine Initiative, Merck talks about the need for downstream processing within vaccine production.
Pattanik
Challenge
The production of vaccines can be one of the most demanding areas of pharmaceutical manufacturing, due to very high pressure to keep costs down, the stringent safety measures associated with targeting a healthy population, and the complexities of vaccine molecules themselves. As such, downstream processing and purification steps are crucial to the vaccine manufacturing process, with purification steps accounting for up to 80% of the manufacturing costs.
Most of the purification processes used in vaccine manufacturing today are time-consuming, expensive and result in unimpressive yields. Many of these drawbacks are a result of the multi-step purification process to which the product is subjected. This complicated process decreases the yield through product loss at each step, increases the time the product is in contact with impurities, and risks damage to a potentially fragile product.
For these reasons, optimising the purification process for cost and efficiency is a necessary step toward accelerating availability of affordable vaccines, and manufacturers are eager to develop purification methods that are more robust, economically viable and sustainable than what is currently available.
In support of this goal, Merck has joined the DiViNe project, a European consortium of six companies (Instituto de Biologia Experimental Tecnológica, Portugal; Affilogic SAS, France; Aquaporin A/S, Denmark; Genibet, Portugal; GlaxoSmithKline, Italy, and Merck KGaA, Germany) that have joined forces to address the biggest challenges facing the development, manufacture and delivery of vaccines.
The objective of the DiViNe Consortium is to create an integrated, cost-effective purification program specifically tailored for vaccines that achieves higher yields while preserving product integrity.
The DiViNe Concept
The concept behind the DiViNe Consortium is to apply affinity chromatography to the highly demanding application of vaccine production. Affinity chromatography is a separation method based on a specific binding interaction between an immobilised ligand and its binding partner such as antibody/antigen, enzyme/substrate, and enzyme/inhibitor interactions. The degree of purification can be quite high depending on the specificity of the interaction and, consequently, it is generally the first step, if not the only step, in a purification strategy.
While most chromatography resins are designed for the purification of proteins, which have a low molecular weight, the viruses, virus vectors and polysaccharides used in vaccines are large molecular entities. As such there is a need in the market for chromatography resins with the appropriate separation index to separate these macromolecules.
The DiViNe Consortium partners will combine two major nanotechnology innovations (Affilogic Nanofitins ligands for affinity capture and Aquaporin Inside membranes for fluid recycling) to develop an integrated purification platform amenable to diverse, heterogeneous types of vaccines including glycoconjugates, protein antigens and viruses.
Members of the consortium will share their particular expertise in vaccine production.
Merck’s specific focus will be on simplifying the process of affinity chromatography by developing resins with the correct separation index for large molecular entities. In support of this goal, the company will be providing chromatographic materials and coupling technologies to immobilize the Nanofitin® affinity ligands. The most promising materials will be optimized regarding dynamic binding capacity, operational stability, and process economical aspects. Further engineering of the Nanofitin ligands will enable enhanced capture performances of the affinity material.
GlaxoSmithKline brings to the consortium a broad range of representative targets that are actual vaccine candidates, and will ensure that purification processes developed under DiViNe project meet industrial needs and expectations.
Affilogic will select Nanofitin candidates based upon their ability to release the vaccine targets under mild elution conditions, without hampering their integrity, and Aquaporin will implement its membrane purification technology for water recycling and reusability.
iBET is project coordinator as well as being responsible for process validation, including quality control (QC) and up- and downstream integration. The synthesis of the final prototypes will be scaled up into multi-liter scale.
GenIbet Biopharmaceuticals will perform all required QC testing and be responsible for cGMP manufacturing compliance. Taking into account quality and regulatory requirements, they will identify a path to validate this global, compliant, environment-friendly process for vaccines manufacturing.
Impact
The downstream process for vaccine targets comprises multiple steps: precipitation, folding, filtration, chromatography and crystallisation. Affinity capture implementation has already proven extremely successful in the purification of monoclonal antibodies, with a potential to increase purified product yields from 10% to 90% at the stage of affinity purification alone. Based on the improved yields delivered for monoclonal antibodies, a three to five-fold increase in overall recovery yield is expected when the technology is applied to vaccine targets.
A major objective will be the simplification of the purification workflow by reducing multiple steps to two to three consecutive operations centred on affinity capture as the primary purification method. By reducing the number of steps, the goal is also to reduce operational costs. Moreover, Nanofitin ligands are easy to manufacture, reducing the cost-of-goods, while Aquaporin Inside™ membranes will be available by the roll for increased convenience.
The low manufacturing costs of such elements also make them compatible with a single-use approach, which can be even more cost-effective, as simply using them once and disposing of them will help save the time, fluids and verification steps induced by any cleaning in place (CIP) protocol required for cleaning and reusing columns. This is of particular significance for infectious, virus-based vaccines for which contamination and carry-over are serious concerns.
To address harsh elution conditions that may hamper the structure of more fragile products (thereby generating new impurities and reducing the yield), Nanofitin ligands can be generated to bind the intended target on a specific epitope even under high concentration of impurities, while eluting the target under conditions compatible with product integrity. And Aquaporin Inside™ membranes rely on active water transport, thereby creating almost no pressure nor shear stress. The combination of both technologies allows gentler processes to be implemented.
To address energy-use concerns, water will be purified using Aquaporin technology, which consists of a membrane coated with aquaporins that can purify water while consuming only small amounts of energy. The innovation is based on the natural filtering ability of aquaporins which, contrary to conventional methods, avoid the use of elaborate filtration systems, which are typically based on energy- and cost-intensive hydrostatic pressure. As most fluids will be recycled for reuse, typically in early purification steps, the DiViNe purification process aims to set new standards for water consumption in downstream processing.
By optimising the particle and pore size of the chromatography resin, and immobilising the Nanofitin affinity ligands, Merck expects to deliver a significant increase in dynamic binding capacity, thereby maximising column throughput and improving process economics. The ability to increase capacity and throughput with the chromatography resin will also enable more effective processing of high titers coming from upstream processing.
Conclusion
The DiViNe project seeks to validate a novel, nanotechnology-based, streamlined, sustainable and high yield downstream process for the purification of vaccines. The two major goals of the project will be to enable access to affordable vaccines in particular in emerging countries, and to allow local manufacturing in geographies where the quantities of high quality water needed for vaccine production may not be readily available. By meeting such stringent standards, the combined platform will demonstrate its versatility.
DiViNe partners will combine expertise and technologies to conceive, assemble, test, validate and implement a complete system. This system will be
- Scalable – ensuring adoption at early stages, opening the research-stage market as well as the industrial manufacturing area.
- Product-friendly – mild elution conditions and dramatically reduced pressures will enable the preservation of the integrity of products (enveloped vaccines and fragile antigens particular).
- Affordable – components will be easy to manufacture and the cost-of-goods will be low
- Streamlined – fewer steps will aid in reducing operational cost.
- Easy to implement – available at different scales, with disposable parts and with high performance, it will be adaptable to most existing upstream processes in existing facilities.
- Sustainable – as most fluids will be recycled for reuse in early purification steps, contributing to a minimal environmental footprint.
- Broadly applicable – selected vaccines represent a set of targets amongst the most complex to handle, therefore custom development can be implemented on biological products at large
Through such demonstration on the most representative vaccines (glycoconjugates, protein antigens and enveloped viruses), the consortium will establish a sustainable platform to design custom, affordable, industry-compliant and environment-friendly purification processes of biologics. The target market will broadly expand beyond vaccines, up to complex recombinant products, gene therapy vectors, or blood products.