Application of ATR-FTIR imaging to industrial scale production of therapeutic antibodies

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Biopharmaceuticals, proteins used as drugs, are an emerging area in the treatment of a range of diseases. The large scale production of these molecules requires a number of discrete steps including recombinant expression, isolation by a technique called column chromatography and development of an optimal final formulation. The isolation of the biopharmaceuticals from all other contaminating material usually involves a number of steps. The column chromatography used exploits a specific interaction between the target protein and another molecule immobilized on a support, the resin. Ideally all the contaminating material is washed from the column and the conditions are changed in order to release the protein from the resin. Optimal binding, washing and release steps often require significant changes in the properties of the surrounding solution, for example pH and ionic strength. In addition, it is possible to bind very high concentrations of the protein onto these resins. The concentrations reached are likely to be higher than those achieved at any other point in the production process. It is not known exactly what effects the different solution conditions and protein concentrations have on the quality of the protein. Indeed they may result in highly undesirable effects such as non-specific aggregation. Another key issue that scientists isolating biopharmaceuticals encounter is the binding of unwanted contaminant materials which reduces the ability of the column to isolate the target protein. Regular replacement of the resin significantly increases the cost of the isolation process and thus of biopharmaceutical production. Here we aim to investigate these issues with a view to improving isolation protocols using a specialized technique called Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy. This technique allows us to chemically image (take chemical photographs of) the target protein molecules under different conditions both in static droplets and in dynamic systems similar to those used for large scale isolation. We can also directly image used resin with a view to understanding what contaminating molecules reduce the useful lifetime of the material. We anticipate that the results of these experiments will inform optimization of isolation protocols to both minimize target protein losses on-column and increase resin lifetime.