Aggregation of Recombinant Human Granulocyte-Colony Stimulating Factor (G-CSF) Under Process Conditions

Granulocyte-colony stimulating factor (G-CSF) is a cytokine which is therapeutically used in oncology and hematology. It tends to form soluble and insoluble aggregates particularly under high-stress conditions that occur during the pharmaceutical production process. Aggregates of therapeutic proteins can cause severe adverse reactions after administration, but they also reduce shelf life and pharmacological activity. Prevention of protein aggregation in drug formulations is of considerable importance in pharmaceutical industry. Therefore high effort for optimization of formulations is necessary to obtain an optimum of protein stability. Knowledge about the mechanism and the process kinetics of G-CSF aggregation could enable the improvement of algorithms for the prediction of protein aggregation and lead to cost reduction of formulation development. The simulation of process conditions was accomplished by agitation and exposure of G-CSF to gas-liquid interfaces. Size exclusion HPLC was employed to quantify aggregates and to monitor their formation over stressing time. Intrinsic fluorescence, SDS-PAGE and mass spectrometry provided qualitative information on the protein aggregates and their formation mechanism.