Optimization of a preparative multimodal ion exchange step for purification of a potential malaria vaccine

• The critical process parameters could be identified and quantified.
• The binding of the target product was exclusively in hydrophobic interaction mode.
• A product recovery of 61% and purity PP1e2C of 60% can be achieved.
• The model created is suitable for the prediction of future experiments.

In 2000 the implementation of quality by design (QbD) was introduced by the Food and Drug Administration (FDA) and described in the ICH Q8, Q9 and Q10 guidelines. Since that time, systematic optimization strategies for purification of biopharmaceuticals have gained a more important role in industrial process development. In this investigation, the optimization strategy was carried out by adopting design of experiments (DoE) in small scale experiments. A combination method comprising a desalting and a multimodal ion exchange step was used for the experimental runs via the chromatographic system ÄKTA™ avant. The multimodal resin Capto™ adhere was investigated as an alternative to conventional ion exchange and hydrophobic interaction resins for the intermediate purification of the potential malaria vaccine D1M1. The ligands, used in multimodal chromatography, interact with the target molecule in different ways. The multimodal functionality includes the binding of proteins in spite of the ionic strength of the loading material. The target protein binds at specific salt conditions and can be eluted by a step gradient decreasing the pH value and reducing the ionic strength. It is possible to achieve a maximized purity and recovery of the product because degradation products and other contaminants do not bind at specific salt concentrations at which the product still binds to the ligands.