Determination of Critical Quality Attributes for a Biotherapeutic in the QbD Paradigm: GCSF as a Case Study.

Estimating impact of the various product-related variants and impurities on a biotherapeutic's safety and efficacy is an essential requirement in the quality by design paradigm. In view of the limited role that clinical studies offer in this regard, we demonstrate a preclinical approach to achieve this for granulocyte colony-stimulating factor (GCSF). While our repeated-dose toxicity data suggest that these variants do not elicit any adverse effects or histopathological changes, aggregated GCSF impurity caused sluggishness in animal behavior manifested by a possible muscular injury. Cell assay data revealed that the cys-64-cys74 disulfide bond in reduced GCSF imparts stabilization in absence of the cys-36-cys42 bond. PK data demonstrate variability in half lives of different species when compared to the native GCSF. PD data along with differential expression of JAK-2 and STAT5a genes show that all the tested variants triggered the required signal transduction pathways for neutrophil proliferation and activation.