The development of recombinant antibodies and vaccines has allowed us to treat and prevent a
large number of life-threatening diseases. However, as things stand in 2015, the speed, capacity
and scalability of current production systems is beginning to place limitations on this crucial
technology. The large-scale production of antibodies, vaccines and other pharmaceutical
recombinant proteins is restricted by the industry’s current reliance on fermenter technology,
particularly the culture of mammalian cells. This expensive and time-consuming production
platform is preventing the distribution of recombinant protein drugs to those most in need. One
way in which the above limitations can be addressed is through the use of plants and plant-based
expression systems for rapid recombinant pharmaceutical protein production.
The economic production of plant-based pharmaceuticals depends on satisfactory yields and
product quality. This presentation will discuss the latest development in antibody and vaccine
development and their production by molecular farming, focusing particularly on strategies to
maximize protein yields during upstream production and optimize protein recovery in the
downstream processing steps. Such strategies often involve careful consideration of how the
protein is expressed and targeted within the plant cell, a factor which affects yield, stability,
quality and ease of isolation. Our long-term objective is to ensure that next generation of plantbased
production systems for recombinant proteins will create the opportunity to deliver
antibodies, vaccines and other biopharmaceuticals beyond the industrialized nations and into the
developing world. Several case studies will be presented: HIV antibodies were chosen to
undergo fast-track development, including risk assessment, expression in tobacco, scale-up,
downstream processing and regulatory development, with the aim of performing clinical trials. In
addition use of engineered plant cells for human vaccine candidates will be discussed.
Pharma-Planta is an EU Sixth Framework Integrated Project whose primary goal is to develop an
approved production pipeline for plant-derived pharmaceutical proteins (PDPs). Although
previous research has provided proof of the PDP concept, Pharma-Planta aims to develop an
entire production chain by taking candidate pharmaceutical molecules from the expression
platform through all stages of production and processing, ultimately to initiate phase I human
trials in Europe. The Pharma-Planta Consortium comprised 40 interacting groups representing 33
public institutes and SMEs from 11 European Member States and South Africa.
At the beginning of the project, eight target molecules were chosen representing four key
indication areas including HIV. From these molecules, two HIV antibodies were chosen to
undergo fast-track development, which would include risk assessment, cloning, expression and
optimization of production in plants, scale-up, downstream processing and regulatory
development, with the aim of submitting at least one of them for clinical trials within the five
years of the program. Two HIV neutralizing antibodies have been expressed successfully in the
two main production crops being developed within the consortium – maize and tobacco. One of
these antibodies, 2G12, has been expressed at levels greater 100 mg per kg of plant material. The
plant-derived antibodies remain stable and functional and retain their neutralizing activity. The
consortium has investigated novel upscaling and downstream processing strategies to provide
multiple grams clinical grade antibody material for human clinical trials. Preclinical trials in
rabbits have been completed successfully and we also conducted successfully a phase I clinical
trial in the UK. This work will now be moved forward for a phase IIa clinical trial which is
funded by an Advanced ERC grant from the European Commission.
We have also developed an interesting multi-stage malaria vaccine and neutralizing rabies
antibody candidates and will discuss how both products have matured over the years both in
performance and in manufacturing with the aim in mind to bring these two products into
translational research within the next months.
Finally state of the art technology developments to accelerate the development and production of
PMPs as well as regulatory issues will be discussed. Along this line an innovative new
manufacturing concept using LED lighting in a vertical farm concept have been developed.
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