Development of predictive tools and formulations for improved stability and delivery

Project Description:
Industry traditionally develops biotherapeutic recombinant protein and peptide formulations to stabilise and deliver such drugs by undertaking pre-formulation studies that identify drug concentration, excipient, buffer and other formulation conditions that provide a formulation fit for purpose (i.e. one that has the required stability and can be delivered in an active form without degradation of the bioactive drug). Traditionally the development of such formulations is undertaken using design of experiment approaches to screen a large number of potential variables and 'identify' a 'suitable' formulation for a specific product. This approach generally works well for established biotherapeutics, for example monoclonal antibodies (mAbs), where historical knowledge is used as a starting point in the development of a new molecule, although even in this field for some molecules it can be difficult to stabilise the molecule at the desired concentration. For non-mAb biotherapeutics it can be more challenging to design appropriate formulations due to the divergent nature of the molecules, lack of historical data on these and our general limited understanding of the relationship between stability, recombinant proteins/peptides and formulations.
In this project we will investigate two classes of non-mAb based biotherapeutics, peptides and heavy chain fusion proteins, and the influence of residue host cell proteins and excipient conditions on subsequent stability using accelerated and long term stability studies. The student will express in CHO or E. coli cells model peptide and heavy chain fusion proteins (milestone 1) and then purify these using affinity and ion exchange chromatography (milestone 2). The student will use mass spectrometry, ELISA and gel based approaches throughout the purification process to determine the amounts of host cell protein remaining and relate this to subsequent stability of the molecule under standard accelerated stability studies (as required for regulator approval of final products) monitored by DSC, CD, particle formation analysis, size exclusion chromatography, cell based activity assays (where appropriate) and mass spectrometry (milestone 3). The purified materials will then be subjected to design of experiments analysis of formulation variables at MedImmune using standard industrial procedures to develop and test formulations for biotherapeutic products (milestone 4). In silico analysis will also be undertaken to highlight potential amino acids or areas that might introduce instability into the molecules and site directed mutants of these produced and related to stability using the design-of-experiments formulation screen (milestone 5)The proposed programme of work will improve our understanding of the molecular mechanisms by which proteins may be stabilised. We also note that trained formulation scientists in biotherapeutics (as opposed to small molecules) are difficult to recruit in the UK and that this is an area of Bioprocessing. This project will train a formulation scientist and further our understanding of the issues preventing stable formulation of a number of key therapeutic target molecules. This project arises as a direct result of a successful collaborative PhD studentship between the two institutes in formulation studies.