Tailor-made expression hosts depleted in protease activity for recombinant protein production; PRODuCE (PROtease Depleted CEll line)

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Small molecule drugs (e.g. antibiotics) have traditionally been the mainstay of treatments and therapies in man. However in the last 10-20 years protein based drugs (e.g. Herceptin, often used to treat breast cancer, insulin) have been developed such that these now constitute the fastest growing section of the pharmaceutical market. There are several categories of protein-based drugs, many of which are produced from cultured mammalian or yeast cells at an industrial scale. Due to the high precision required to produce such biotherapeutics, such 'recombinant' protein-based drugs (biopharmaceuticals) are usually produced by cells kept in culture under defined conditions. One problem with this is that the cells scientists use to make proteins for therapeutic uses also make their own proteins including proteases whose expression can be detrimental to the production of therapeutic proteins. These types of proteins can actually degrade the target recombinant protein making them useless in a clinical sense. As a consequence, scientists may not be able to produce enough of these drugs and/or the cost of producing them may be too high, thus precluding health care providers from recommending their use. This proposal sets out to address a key area that underpins recombinant protein synthesis from cultured mammalian and plant cells. We aim to develop a comprehensive knowledge of the detrimental proteolytic activities in different cell lines (animals and plants) used for the production of biopharmaceuticals. We will use state-of-the-art approaches and technologies to define those proteases that are detrimental to recombinant protein production from these expression systems and then utilise this knowledge to reduce or eliminate the amount of these in the host cells. This will ultimately result in less or no proteolytic cleavage and damage of the therapeutic protein being produced. This programme therefore proposes to address the gap in our understanding as to the importance of proteases in defining product quality and yield. The overall aim is to generate new cells and systems that exploit manipulations of the cells proteolytic machinery to enhance the production of recombinant therapeutic proteins at the industrial scale. This information is of very substantial relevance to industry since the production of commercially valuable therapeutic proteins is potentially hindered by these detrimental reactions. Without improved expression systems, the biotechnology/pharmaceutical industries will lack the capability to produce large enough amounts of these valuable and effective drugs to meet the demand at a price that will allow them to be prescribed for all patients who would benefit from them.